Not enough reward in the mechanics, I played about 50% of the archive games and each was the same. A feeling a frantic pressure and an inability to hit the 18 words every time (i.e. I lost)
Maybe I'm just too slow, but I feel like a good game should cater for players of mixed ability. This one seems stuck in pro / turbo mode and left me feeling frustrated - which is the only thing really thats stopped me bookmarking it or sharing with my family.
Edit to add - Boggle also has a timer and puts you pressure. But there's multiple paths through the grid which means your less likely to hit a brick wall and also allows for small side wins that help you along (e.g oh there's another three letter word when I am really looking for a 5 or 6).