Fun start but slows and drags later. It finishes with only novelty fun of space conquering and abducting stuff.
Cell stage - cute and original. Very fun because you do not have to play it long and given the context, it is excused from having many options. You start off as a tiny cell and slowly get bigger and more parts to fight move and survive with. Growing bigger is quite psychedelic.
Land stage - Entertaining as hell at first, going from a land noob to a land dominator. The fights end up exactly like an MMO though, and a lot of the parts make you choose between what you want to look like and how high a level you want a skill >_>. The creature creator is quite innovative and loose, but in the end, you can only adjust the spine and its thickness to give the body proportions, and add parts on to it (the parts can be morphed too). everything is round and bulbous as far as the main body itself is concern. Also, friendly interaction is reduced to a simon says game, and if you can't "dance" well enough you have to get better feet, or if you can't seing well enough, you have to get a better mouth?...
tribal stage - simply a veryyyyyyy weak rts with a civ like option of befriending a tribe instead. No more creature adjustment at this point, only clothes...
Civ stage - just plain
space stage - goofy fun, and charming how you get to plant different things on to new planets, but yeah...
As a whole package, its fun since it goes from the very core beginning to the end. Touching on many genre such as action, rts, rpg...ish
In the end, I personally would of just liked the first 2 stage made into its own game and have its complexity cubed. Sorta like the evolution game on dreamcast, and the evo game on the snes. Maybe throw in tribal stage too. But given the hype and legacy of its creator, the game is just adequate.