What is best quality of demos out there, currently i know Bathroom demo, BlenderDoom and Krum but maybe i have missed some demo with such high quality like those are?
You could always check out the sticky in the Game Engine WIP thread.
Not to toot my own horn, but… http://blenderartists.org/forum/showthread.php?t=129465 
Seriously, look at the WIP thread. Many of the games there aren’t complete, but they’re usually very cool nontheless.
Pretty much anything that Endi does is VERY, VERY good.
I second that.
what! dose krum got a DEMO! where can I find it? 
i hace checked lot lot of topics but there is nothing similar to BlenderDoom and Bathroom, these 2 graphics and physics is stunning like crysis or ut3 interior. Krum is very good without shaders like some playstation 2 game.
endi & martinsh threads .
That`s because those new shiny features are added just very recently, you can check out “Duk, Duk” and “Me and My Airship” threads, these have very nice graphics and style without using GLSL and dynamic shadowmaps.
Dont forget Endi’s city level:
http://blenderartists.org/forum/showthread.php?t=133471&highlight=city+level
Now that is new to me and its comparable to other BlenderDoom and Bathroom, thanks.
Yes, i have a sneaking suspicion that that one will be in the gallery soon, too… 
How about martinish’s ‘checkpoint racer’ ?
Quite nice, it would be better if she would use 2.48 engine with GLSL