On browser first- It's visually very nice, and satisfying to move objects around. However I only was able to make a few items and got really bored of trying and being constantly rejected. I didn't see a hint system, items vibrated, but then the next vibrating item didn't combine with them so unsure of how you're supposed to know what you need to do.
On phone no new comments, it feels fine. It was buggy to place a second item in the grid when there was a text box overlay, but closing the text box resolved the issue.