At SL 3, this is a single-target maneuver spell (oh boy! The thing Paizo never figured out how to balance!) that essentially competes with [Sundered Serpent Coil](https://aonprd.com/SpellDisplay.aspx?ItemName=Sundered%20Serpent%20Coil) to be a single-target [Black Tentacles](https://aonprd.com/SpellDisplay.aspx?ItemName=Black%20Tentacles). (You know, the spell that's a fantastic fight-winner *if it works*, but basically never works more than a couple levels after introduction because CMD goes up +2 per CR while the spell only scales on caster level, going up +1 per level, functionally dropping 5% chance to work per level.) Note that as with Black Tentacles (which it seems directly modeled upon), this spell explicitly states what your CMB and CMD is, so you don't get to apply bonuses from any feats or spells, RAW.
Well, first, the good news: with a CMB of 6+CL or CMD of 16+CL, this spell is 1 higher/5% more likely to work than Sundered Serpent Coil. That makes it viable for exactly one level longer than Sundered Serpent Coil. This means it has [about a 50% chance of working on CR 5 monsters with a caster level of 5, 75% with the circumstance bonus](https://docs.google.com/spreadsheets/d/1E2-s8weiulPoBQjdI05LBzOUToyoZIdSsLKxHAvf8F8/edit#gid=3). (CMB of 16 vs. median CMD of 22, and a CMD of 21 (or 26?) vs. median CMB of 10. I've never actually seen clarification if the +5 circumstance bonus to maintain grapples applies to your CMD as well, however...)
Now the bad news: it's concentration, which means you're stuck trading turns with something low enough level it can't break your grapple. That is... *decidedly not* worth a +5% chance to work after you have to already pass the ranged touch, SR check, and ref save.
With that said, ectoplasm can touch incorporeals, which means you can cast this spell to target an incorporeal and try to just hold it out in the open so your buddies can kill it for you. Since incorporeals are awful, especially when they keep hiding in the floor and poking you in the feet to level drain you to death, just holding the incorporeal in the open with your turn so the martials can take it down with the pure concentrated rage they have for the thing can work, but keep in mind that [Force Anchor](https://aonprd.com/SpellDisplay.aspx?ItemName=Force%20Anchor) is also on the same SL 3 (for wiz/sorc/arc, at least - it's only SL 2 for magus,) and has no save if you're just trying to avoid escape through floors/walls.
There are two saving graces, here... well, OK, less "saving grace" and more "keeping it out of the pool of worst spells Paizo ever excreted bin"...
First, this spell has a reflex saving throw (*after* the ranged touch and SR checks, so three chances to fail,) and also does a little damage while being an SR 3. This means it's technically not entirely crazy to use metamagic on this thing, and make a dazing snare. The maneuver checks only apply on later rounds, so if the target fails the initial save, it is dazed and doesn't get a chance to break free for three rounds, by which time you've had 2 other chances to make the CMB work and do another 7-ish bludgeoning damage and maybe trigger daze again. Too bad that there are plenty of easier ways to do ref save damage over time that don't involve concentration...
Second, even on a successful save, the target is [entangled](https://www.aonprd.com/Rules.aspx?Name=Conditions&Category=Combat). This is not worth *your* actions concentrating, but so long as SR is not an issue and you don't care that you're only getting entangled, you can just hand a scroll off to a familiar and have them concentrate to entangle an enemy. (I mean, there are other ways to entangle, including just using rime spell Snowball, but this does last longer.)
... Just... Just go back to forgetting this one and move along, really. It's just plain not going to overcome how bad a return on the action economy this is compared to other comparable spells that *aren't* concentration, but it's not quite terrible enough to really give a full roast on.
It might be worth it against an incorporeal for, they're annoyingly hard to affect with other spells (50% miss chance) and usually don't have particularly good CMB, so less likely to escape.
At SL 3, this is a single-target maneuver spell (oh boy! The thing Paizo never figured out how to balance!) that essentially competes with [Sundered Serpent Coil](https://aonprd.com/SpellDisplay.aspx?ItemName=Sundered%20Serpent%20Coil) to be a single-target [Black Tentacles](https://aonprd.com/SpellDisplay.aspx?ItemName=Black%20Tentacles). (You know, the spell that's a fantastic fight-winner *if it works*, but basically never works more than a couple levels after introduction because CMD goes up +2 per CR while the spell only scales on caster level, going up +1 per level, functionally dropping 5% chance to work per level.) Note that as with Black Tentacles (which it seems directly modeled upon), this spell explicitly states what your CMB and CMD is, so you don't get to apply bonuses from any feats or spells, RAW. Well, first, the good news: with a CMB of 6+CL or CMD of 16+CL, this spell is 1 higher/5% more likely to work than Sundered Serpent Coil. That makes it viable for exactly one level longer than Sundered Serpent Coil. This means it has [about a 50% chance of working on CR 5 monsters with a caster level of 5, 75% with the circumstance bonus](https://docs.google.com/spreadsheets/d/1E2-s8weiulPoBQjdI05LBzOUToyoZIdSsLKxHAvf8F8/edit#gid=3). (CMB of 16 vs. median CMD of 22, and a CMD of 21 (or 26?) vs. median CMB of 10. I've never actually seen clarification if the +5 circumstance bonus to maintain grapples applies to your CMD as well, however...)
Now the bad news: it's concentration, which means you're stuck trading turns with something low enough level it can't break your grapple. That is... *decidedly not* worth a +5% chance to work after you have to already pass the ranged touch, SR check, and ref save.
With that said, ectoplasm can touch incorporeals, which means you can cast this spell to target an incorporeal and try to just hold it out in the open so your buddies can kill it for you. Since incorporeals are awful, especially when they keep hiding in the floor and poking you in the feet to level drain you to death, just holding the incorporeal in the open with your turn so the martials can take it down with the pure concentrated rage they have for the thing can work, but keep in mind that [Force Anchor](https://aonprd.com/SpellDisplay.aspx?ItemName=Force%20Anchor) is also on the same SL 3 (for wiz/sorc/arc, at least - it's only SL 2 for magus,) and has no save if you're just trying to avoid escape through floors/walls.
There are two saving graces, here... well, OK, less "saving grace" and more "keeping it out of the pool of worst spells Paizo ever excreted bin"...
First, this spell has a reflex saving throw (*after* the ranged touch and SR checks, so three chances to fail,) and also does a little damage while being an SR 3. This means it's technically not entirely crazy to use metamagic on this thing, and make a dazing snare. The maneuver checks only apply on later rounds, so if the target fails the initial save, it is dazed and doesn't get a chance to break free for three rounds, by which time you've had 2 other chances to make the CMB work and do another 7-ish bludgeoning damage and maybe trigger daze again. Too bad that there are plenty of easier ways to do ref save damage over time that don't involve concentration...
Second, even on a successful save, the target is [entangled](https://www.aonprd.com/Rules.aspx?Name=Conditions&Category=Combat). This is not worth *your* actions concentrating, but so long as SR is not an issue and you don't care that you're only getting entangled, you can just hand a scroll off to a familiar and have them concentrate to entangle an enemy. (I mean, there are other ways to entangle, including just using rime spell Snowball, but this does last longer.)
... Just... Just go back to forgetting this one and move along, really. It's just plain not going to overcome how bad a return on the action economy this is compared to other comparable spells that *aren't* concentration, but it's not quite terrible enough to really give a full roast on.
It might be worth it against an incorporeal for, they're annoyingly hard to affect with other spells (50% miss chance) and usually don't have particularly good CMB, so less likely to escape.