I really liked the atmosphere, i.e. the music, sound, and visual style. The puzzles are creative and always seem reasonably challenging. I always felt a sense of accomplishment as I played through the game.
Unfortunately, the game has two very frustrating sections that can definitely ruin the experience, so I'll just warn you about them. The second and third numbered puzzles in the mines seem to require that you make the nozzle that lets you create fluro blobs, but there's no indication from the game that you will ever need a certain upgrade in order to progress. You need that nozzle because it lets you shoot fluros through the grates, but there's no hint from the game that you can do that. It's very frustrating if you get stuck and keep trying to shoot green goo through grates, which you're clearly not supposed to really be able to do. Also, on the section with ladders, it turns out that you can use one of the nozzles (the one that propels you a little bit) to make the jumps easier, but the game doesn't really hint very well that you can use that nozzle to do that.
Secondly, for the final part of the game (the accelerator) you should probably just use a walkthrough to figure out what you're supposed to do. The requirements to complete it are very unclear and don't make a lot of sense.
Other than that, the game was one of the most enjoyable puzzle platformers I've played. I'd say I liked it more than games like Braid, Waking Mars, and Fez.