Honestly, I think the big killer here is the palette. The colours are oversaturated, way too bright, and murder on the eyes. Don't get me wrong, as they are nice colours in and of themselves, and there is a time and place for such vibrancy, but I can't imagine staring at this for any length of time without causing some serious eye strain.
The tiles themselves look quite alright; simplistic but effective... I like 'em okay, anyway.
