I wish they had Roots when I was a student at UCSD. Back then the student co-op (which was in the old student center) and Che Cafe had what passed for vegetarian food. It was bland and boring. There was no Price Center with ethnic vegetarian, let alone vegan, fast food places.
Times change, and now there is Roots! I have been there a handful of times, and I must say that it is a good deal for what you pay. The portions are big, and the offerings change with the season. Their menu changes from week to week. You can check it out online: http://hdh.ucsd.edu/DiningMenus/default.aspx?i=32
I usually get one of their Field and Farm salads, which are full of fresh vegetables. Each salad is quite filling, but if I crave more, I get a cup of soup or an order of sweet potato fries along with the salad.
I live near campus so I can easily walk or bike to Roots. I suppose it is a little more challenging if you are a visitor and try to find parking. The Muir parking lot has visitor spots and a self-pay booth, but actually finding a space may be more difficult.
Roots is closed during the weekend and during school breaks as I found out when I made a special trip to Roots over the summer. Go during the school year and enjoy their wonderful food!
Cons: closed on weekends and breaks, visitor parking is scarce