I can't really give a review yet, but what I've played of it is definitely more experiential than you'd imagine. It's a bit impossible to really tell someone WHY Proteus is worth your time and money without having them had already played it, which is of course a catch-22. There's a surprising amount of goal-setting you make for yourself within the game despite there being no real way for you to interact with the game in a direct way and I've ended up putting about 5 hours into it so far.
Also, there's a platinum trophy.
I never played the original PC release, but the Vita doesn't seem like it hampers the experience. In fact, being a more personal type of play, it may enhance the experience.