I've been using the PK301 in my bedroom for about a month now. Overall I'm happy with it but I do sometimes wonder if I'd have been better off just getting a "regular" projector for a tiny bit more and using that instead.
I have a regular lamp projector which I use for my "home theatre" and the brightness and sharpness just doesn't compare.
The PK301 certainly isn't going to be much good as your main home theatre projector. It's simply not bright enough and you can never really get things perfectly focussed.
I've connected it to my macbook (mini-HDMI to HDMI>apple adapter) and can browse Youtube and such like without any problems. Even at 80+ inches the text is readable - but it's not perfect, it's a tiny bit blurred.
I use the PK301 in my bedroom, mainly for watching cartoons (futurama, simpsons, family guy, etc.). For cartoons with bright colours it is fantastic, but I find it a bit too dark for most movies (even with a pitch black room).
It does get hot but so far I haven't had any issues with it. The longest I've ran it at a time is probably 4 hours in a room which has a temp of ~30 degrees celcius.
I'd never use this projector running only on the battery. The video comes out pink and very dim!