Entertaining
I thoroughly enjoyed this game. I am sad to admit that I don't recall ever having played the game Lemmings, but if it is similar to this concept, then I'm sure I would enjoy that one as well.
The levels progress well in difficulty and in increasingly requiring you to think around and, in the cases of level 13 for me, outside of what you would automatically think of doing with the available skill sets. A glitch that i came across was that if a climber came across the base of a stair that went over its head (i.e, it couldn't walk up them), it would then climb the air until it disappeared out the top of the screen; a wee bit annoying, but then again having a climber in that situation probably indicates that the level wasn't going so well for you to begin with. So. I don't think that is worth subtracting a star for.
The "speed" button, however, seems to be a bit off; as best as I can tell, the students just don't walk the same number of steps/second in speed mode as they do in regular mode. I may be wrong, but when I used the button I ran out of time, particularly on level 10, with all the pillars. I left off of it, and I made it through with time to spare. *shrug*
Overall, a challenging game that requires a good sense of timing and understanding of what the various abilities will do. I also enjoyed that the students were all different; that also made it helpful in differentiating who had what at certain points. Good stragety game.