Hi,
I'm having the same issue but putting the texture to "compressed" didn't fix the problem.
Do you know what could fix the issue? I'm quite new to NGUI.
I have unity 3.5.5f3 free version, I bought and downloaded NGUI a couple of days ago, so I should have a very recent version.
Again, my issue:
Everything looks fine in the editor. I build the game, run in it in the webplayer and in the web player the whole interface looks very blurry.
I tried to override the export settings for the atlas texture , putting 4K + compressed without success.
See the 2 screenhots I did:
Editor Version:

WebPlayer Version:

Thanks for the help
Rampa
EDIT: Putting the graphic settings to "fantastic" fixed the issue. But is there a way to have this working even with minimal graphic settings?