I've got a '58 plate FZ6 (the half-faired Fazer) S2 and the normal complaints seem to be clunky gearboxes ("they all do it sir"), and wind noise at speed (I find it ok up to 70-ish, much more and it does annoy). That said, I quickly learned to pipe speed down due to the wind noise, and it saved me from a bloody scamera on the A1.
It's maybe a good idea to get a test ride if possible; the earlier carb-fed FZS bikes are widely regarded as being nicer bikes to ride the the later (04-on) injected bikes.
If you do buy, haggle the price down; I paid £3500 for my 2008 bike.
Don't know if your proposed bike has it (mine doesn't, so can't say how well it works) but there was an ABS option from 2006 - not something that suits everyone. I've also got a Givi topbox rack on mine, and the underseat exhaust can make life awkward to install it.