It's a favourite of mine. And yes, it is essentially identical to shrooms as it is but pharmaceutical psilocin (which converts to psilocybin in vitro... or is that the other way around? pharmaceutical mushroom powder anyway). I find it to be subjectively "lighter" than shrooms physically (cos mushies give me a bit of a squirmy gut sometimes) but the actual trip is very similar for me. As with any psyche, there's never any absolute guarantee of what will happen. The vast majority of the time you'll giggle like a loon and watch the pretty things. Sometimes it will turn out dark and introspective. Sometimes it will turn out light and introspective. Set and Setting are key as with all psyches. Previous trips - good or bad - don't really make much difference to future ones unless maybe you have had an especially traumatic one in which case it pays to take your time and build up slowly.
That and dose. 4-AcO-DMT has a bit of a steep dose:response curve. Up to ~25mg it's almost universally gigglesome, past that and you're more likely to be go into introspective territory. Which by no means results in a "bad" (perhaps more accurately "difficult") trip necessarily. Certainly can do for some but with psyches you quite often end up getting what you expect - or perhaps what you deserve :D - whether that be gigglez 'n' swirlz or... something else.
It certainly has far more potential for introspection than most of the 2C-x series, for example. But saying that it's also one of the most recreational psyches at the right (generally lowish) dose. All this is highly subjective and variable, of course. If you are reasonably comfortable and familiar with psyches it's a winner for sure. If not so sure then it's not a bad option but start low and be cautious about raising the dose too much on subsequent occasions cos small increases in dose can have dramatic increases in effect with this one.