The last single-speed I had was a BMX bike when I was a kid, but from what I understand, fixed-gear bikes are a bit tricky to ride on the street. Personally I like the ability to switch gears and freewheel, but admittedly some of the single-speeds look really cool, and I wouldn't argue that on flat lands they don't necessaily have major disadvantages over multi-speed bikes.

What I would personally do is get a bike with a "flip-flop" hub so I could switch between fixed and free-wheeling, and for god's sake run brakes! I don't think anyone on either side of the brakes/no-brakes debate would say a beginner should go brakeless.