I've been using an @macosx.com account as my main personal email address since the beginning (nearly 2 years ago now) and it really is very good quality. No spam problems, the webmail is smart and reliable, and I've only noticed one outage in that time which was resolved when I checked back half an hour later.
I've just renewed and I would highly recommend them. Having a low cost, constant, and easy to remember email address has been a lifesaver with my numerous moves, ISP switches and so on.
I haven't really tried to use any of the webspace yet, though, so I can't comment on that.