I personally think the Luna class is nice-looking. And quite honestly, it's hard to tell a convincing exploration story in a floating city like the Galaxy. A smaller more spartan ship makes more sense to me.
As far as being canon, I'm pretty sure it is not, but should be. I know a lot of the old novels are ridiculous and contradictory. but the post-nemesis novels are all carefully interweaved, and I think are good for canonization. Especially considering CBS/Paramount seems to have no interest in moving forward with Star Trek, instead offering a Lucas-style prequel. Curse you for introducing that, Lucas! CURSE YOU! lol