I've not used it, and normally ignore any recommendations from people who haven't actually used the phone, but I'm in a similar position to you and am almost nailed on to get the N73 when I get my new contract in a month.
See the N73 discussion forum for ideas and testimonials.
One housemate has got the Nokia 6280 (I think, it's the one with the slider) and that is superb. If for any reason I don't get the N73, I will probably get that instead.
Other housemate has the K800i. He's a big fan and the camera is superb, but there's something about the SE design I don't like, though again I've not used it that much.
A good site I like for reviews is...
http://www.mobile-phones-uk.org.uk/
There are a lot of "dis fone is da bomb" style reviews but a lot of sensible user reviews and the "official" reviews are often very informative and good.
Good luck - let people know what you get and whether it's any good