I finally got around to trying out the wlan on the N93. I took the train from Stockholm to Malmö, which takes four and a half hours, and SJ are kind enough to offer free wlan access (and free coffee) to those of us buy first class tickets.
Getting connected isn't a problem. Just login with the code on the ticket and start surfing. The connection feels pretty slow, but it did when I connected with the laptop too, so this doesn't have anything to do with the N93. Rendering big pages is also pretty slow, but that's to be expected, as I didn't focus on mobile optimized sites.
The browser is really good, except for some stability problems. It crashed on me twice: once when I was trying to login to my gmail account, and again when I logged out. My frequent changes of screen orientation (reading is more comfortable in landscape mode, but typing text is much easier in portrait mode) also seemed to make it a bit confused now and then. Another problem was that I couldn't figure out how to open new windows, although it happily opened a new window when I logged in on the SJ site.
All in all it was a positive experience, and I'll definitely bring the N93 the next time I'm taking a long train trip. It's not like I'm going to bring my 3kg laptop just to surf for a few hours, but the 200g N93 isn't a problem.