Just finished my year in Wills>
The Student Link goes from all the SB Halls to town, not actually that near the uni. However, that's the night time service. If you're lazy then there is a bus going nearer the Uni from outside Wills in the morning.
Wills has a gym and bookroom, but the gym isn't that good at all, and the bookroom is a rather eclectic mix spreading back over 75 years of collecting by random hall members. The library you'll want to use is either the Arts and Social Main, down by the Uni gym, or specific science ones.
Wills is grand, plenty of parties and things. Formal Hall every friday is followed by a disco, then special entry into various clubs around Bristol. In Freshers' week, there are 3 or 4 special events, and throughout the year the JCR organises things (Bond Night is my personal favourite)
Old Quad is generally seen as the better to be in, but I can't tell you about the people, since there's no difference between Old and New in terms of personality. Old Quad rooms are MUCH larger, and have the old oak wood thing going on. New, however, are all ensuite. It's a toss up. I'm an Old Quad-er, so i'm biased! There is a mini competition between the two quads anyway...