Feels good to be a Certified Block Shop Operator. I really like how polished the game feels, it has a clear color palette and style.
I think the puzzles are paced well, maybe the difficulty could ramp up a little faster, but it's okay as is. The last 2 or 3 puzzles are quite challenging and fun. The tutorial expained the basics very well and I understood how to play immediately after completing it.
I think in games of this genre it's important to have a level select screen so you can skip puzzles that you got stuck on and try different ones. Even in a game jam, not everyone is equally good in solving puzzles, but if people were able to skip 1 or 2 levels, they would see more of the game before rating it...
Another idea is adding hotkeys for placing blocks and especially for turning delete mode on and off.
Great job making Block Shop! Good luck with your future projects!