First of all, this was a game with which I had a true love-hate relationship. Why so? well, the hate part comes purely from the controls and that mixed with the theme of the game (jelly floor mechanic). There were times when I was close to rage quit, the controls just feel so off in some of the segments of the game (there were numerous times, when I just dies because of the really overly sensitive and not so accurate controls). Also the only way I was able to play this game with a controller, was to use Joy2Key. Normally control issues like this would be a total turn-off for me, BUT the love part was just so strong, that it made me want to play and play it again until I finished the game.
I'd like to say, that in a way this game is a lot like games 140 and BOXBOY!, not because its mechanics or simple aesthetics, but the fact, that this is a kind of game I'd like to call "concept game". What I mean by this is, that it takes one core mechanic and then explores that mechanic to the fullest, presenting all kinds of scenarios tightly wrapped around that core. And boy, The Floor Is Jelly does it so well, like 140 and BOXBOY! do to their mechanics.
The level and scenario design is just really good, and has a lot of variety between the different challenges the game throws at you. Sometimes the consistency of difficulty level isn't perfect, having some difficulty spikes, but overall the difficulty is well executed, not easy, not frustratingly hard either. Aesthetics are simple but very pleasing to the eye. Music/sounds are also perfect fit for this game. All in all I'd like to say, that this is once again a real gem, that explores mechanics boldly and while doing so, is presenting one of the most enjoyable platformers I've played. You still remember how I trashed the controls in the beginning of my review? Yeah, the other stuff just is so good, that I can forgive the control issues.
tl;dr: BUY IT!