It's OK. Really simplistic. I would love it if the screen actually got wider, the last couple of minutes is just me pressind W+S to go up and down because my fish is twice the size of the width of the screen. Also I didn't like the species that I ate earlier completely disappearing as I grew. They should stay so I have a feeling of 'Hah, had to dodge these guys earlier, now I own them'. Maybe a bit more customization in what species we want to evolve would have been nice too.
Anyway, game is simplistic, it's a fun little minigame but not deep enough to last longer than 10 minutes.