I think it's a good card, but I agree with a lot of the comments so far.
Mana Drain, albeit not a budget choice, is clearly better.
Plasm Capture also costs you twice as much and you need to able to keep that mana up, and then an opponent needs to cast something worthwhile to counter. And then on your turn, you need to be able to use all that mana. Lots of conditions to insure an optimal use of the card.
I'd play
Plasm Capture if my play group was more on the casual side and I was playing a Simic goodstuff deck. PC would help me ramp out some huge creature.