Pros: The tiles move pretty well, and multiple tiles can be moved at a time. The colors provide a nice diversion, and the timer is excellent for those serious about speed solving like I am.
Cons: This is definitely going to be nitpicking, but every time you get a new scramble, it seems like you only get very unfavorable scenarios - many of the lower numbers start on the bottom of the board, and make it so that it forces you to have solves with higher move counts to work those lower numbers up to their positions at the top of the board. There just doesn’t seem to be enough variance in the scrambles like there would be if it was a truly randomly generated scramble, and it just feels like you aren’t getting an accurate average, if you do practice speed solving.
Overall the app is great and if you’re just looking for a 15 tile slide puzzle to solve casually, this has what you need. For more competitive solvers, it feels like the app is fixed to give you bad starting scenarios more often than not, and I wish there was more true variance in the scrambling.