The timer kills this for me too.

Maybe if it counted up I would be less annoyed by it. I like how the NYT does it with their crossword app. If you complete it under some threshold you get a gold star but there's no upper limit on the time.

The Zanagrams game, which AFACK is from the same developer (?), actually does this - it counts up like a stopwatch, then compares your time to the global average at the end.

I much prefer this way, personally at least.