I've got a friend [not me!!] that's interested in using a low-end projector system as an upgrade from his small SD TV. [Low end ~= 1000$] He asked me what sort of things does he need to think about.
The ones I could think of were:
1. What resolution(s) [input & output] are supported by the projector?
2. How bright is the projector?
3. Can you light-control the room?
4. Do you have enough room to project the image you'd like?
5. What are you going to do for audio?
6. What are you going to do for the screen?
7. Get an in-home demo if possible ... otherwise in-store with your material & lighting are needed.
What are the other "standard" things that he needs to be aware of?