Joshua, I take it that there's a budget issue at play here, which the D200 falls nicely into, hence the asking about this older Nikon model.
As a camera for under £400 it's a great buy; pro-spec, great build quality, good resolution and detail plus fast and sure AF. It's probably one of the best digital SLRs to have come out of the Nikon camp. I used one for two years before moving to my D2X - the only reason I moved was for better weather proofing, which is good on the D200 but even better on the D2X. Like Fracster says, where the D200 will definitely be at a disadvantage is where shooting in dimly lit areas (like churches) where everything is cranked up to maximum to get a useable shot.
If you're comparing the D200 against more modern cameras then the shortfalls will soon become obvious; don't listen to the people who say it's no good above ISO 400 - it is fine up to ISO 1000 if you expose correctly in shadow areas - although admittedly, compared against the D300 the difference is great (the D300 is excellent at high ISO). Otherwise, the ergonimics and features are just about the same.
The S5 Pro, which is based on a D200 body but with Fuji sensor and menu system, is supposed to be a great camera for high tonal range situations (weddings etc) and is probably a good option. Don't read too much into the "is it a 6mp or 12mp camera?" argument; they are top bodies that although discontinued, fetch a premium these days because they're good and the accept Nikon glass.
Personally, if you are working to a tight budget then I'd say that for starters you won't go too far wrong with a D200. They're fetching a lot less than £400 these days so they represent good value for a body of that size with those features. You could look at a D300 but that would cost you £700 at least and I take it that money could be better spent on lenses?
