I put up a server around launch called igs unofficial server that shows in the list. I'll keep it up at least until the feature ends. 99 unique players have joined the server since launch.
I joined it first to give it a try, even though no one else was on it. I'm not sure if it was lag or what, but it spawned me halfway in the ground and I couldn't go forward or jump up high enough to get out of it.
So I tried the developer's server instead and that worked much better. It said there were 15 people on the server but I only ever saw one. The game is a little laggy on my PC (which is modest, 2.5GHz dual core, 9800GT). It played well though, for a game that's relatively early in development.
I too am in the "wish it had a Desura key" camp. Though it's not a deal breaker, obviously.
Oh, and as for the BTA extra skins, they're just image files included in a ZIP archive with a readme.txt file telling you where to install them. Easy.