actually, i think it might be quite useful, especially if you are already using a lot off google's features: gmail, calendar, etc. i just started using it this morning and i've already had a lot of interaction with all my friend's just within a couple of hours. it's also good for ppl who have facebook blocked at work.
here's an interesting article for the potential of buzz:
http://blogs.zdnet.com/Hinchcliffe/?p=1212&tag=nl.e550