Maybe a bit late on this one, but just to add to the general consensus... I've lived in W. Dulwich for 3 years, & it's nice.
Not much going on there, but transport's good; trains take 10 mins to Victoria every 1/2 hour (or about 4 mins to Brixton, 2 mins to HH). You can walk to HH in 15 mins, or get the bus if you're lazy (tho' often ends up taking about the same time). Oh yeah, plus there's a handy night bus that runs from Oxford circus thru' Brixton & up Croxted road, which is v. useful; get back from the middle of town at 2am in 35 mins or so.
Shops/food wise, as people have said, there ain't much aside from the wee Tesco's, which is ok apart from the queues at peak times, & aside from the country-pub-feeling-pub in Dulwich village, the pubs pretty much suck (unless there's somewhere i've not discovered yet!).
But it's very green, the air feels fresher than most places further into town, you've got various parks at your disposal (within walking distance: 2 parks in Dulwich, Brockwell park, Crystal palace is a bit of a walk but easily do-able). It's well peaceful, which is good & bad... good in that you're pretty much guaranteed no stress, no hassle... bad in that it *can* feel a bit middle aged/boring, but then personally these days I prefer to go find excitement when I feel like it & have things calm the rest of the time.
Herne Hill would be really nice if you can afford it; much more in the way of shops etc., tho' bit more hectic.
W. Norwood's always struck me as a bit crap... the high street feels kind of bad & it feels as though you'd get the roughness without any compensating excitement.... but then I've never really spent that much time there other than going to various shops, so the back streets could be lovely for all I know.
I always thought Brockwells looked a bit posh for the likes of me... 
thats my local in theory!
