I spent 5.5 years at UT for undergrad and lived in three different areas. Here's my take:
West Campus - I agree with the above poster on all points. It is definitely overpriced, especially with all the new development. On the other hand, it is extremely convenient to get to campus.
North Campus - This was by far my best housing experience. I lived down on 51st street and then on 30th. It certainly was cheaper than west campus and I found the students much more tolerable. I also enjoyed the walks to campus when I lived on 30th. Its walkable from 33rd or 34th street on in, probably a little further out too.
Riverside (east of I-35) - It is certainly cheap, I'll give it that. The big student complexes are convenient but I think they tend to get a bit rowdy. If you do consider this, I would only look at the complexes that are on the UT shuttle routes. I believe the area south of Riverside (Oltorf street) may be a little better in terms of the roughness of the area, but I don't think they have a UT shuttle. In my opinion, this area isn't that far away from campus. Far West, now that is far.
Some other suggestions - Many students who don't live on a shuttle or live far away drive and park on one of the shuttle routes. If I could do it all over again, I would probably like to live along Enfield or Lake Austin shuttle routes. Then again, those areas are more expensive.