The tyres on my 2004 were awful, particularly in the wet.
You can get new tyres for £20-30 so worth spending if yours are the same.
The wheels are basic, just as they would be on any £500 bike, the same would be true of a Trek, Giant, etc
So if you have a spare £150-200 knocking about, replace with something better. If you haven't, they'll do you fine.
I'd recommend getting some clipless pedals, whatever sort you prefer.
(this forum, as any other, will have lots of people telling you SPD's are brilliant/SPD's are rubbish/buy Looks/don't buy Looks/get Speedplay/don't/etc - get whichever you prefer)
If the saddle suits your *rse then it's a good saddle.
Brake blocks, chain, etc replace as they wear out.