I've had a 5800, 5530 and an X6 all buggy, and what I mean by buggy is browser exiting, and general slowness. Have Nokia gone down hill badly or is it just bad luck on my part?

They are no more buggy than any other make and far less buggy than some.

My work phone is an ancient 6230i and my personal one is an N900. Between the two of them the only bug I've come across is the podcast app on the N900 very occasionally crashing (and I'm not sure if that's even an official Nokia app or not)

So no, not in my experience...

yeah my 5month old 5230,,just decided to be an ass,after software update,heard many groans on nokia forums

My iPhone 3GS has more bugs than a deserted sugar factory, in the Australian jungle, in the middle of summer.

Which bugs ate those?

I've had a 5230 for about the same length of time. a few minor irritants on its original firmware, but no show stoppers. Overall the 5230 has been about as close to perfect as any phone I've ever owned.

So as another has said, they're no more or less buggy than anything else out there. In fact there's very little in software development thats bug-free.