Mmm, that campaign felt goood ^_^.
I think the amount of dialogue was fine - pilots will chatter and you might not hear all of it. It makes the pilot feel (realistically) less important than when all the dialogue is purposefully directed at you.
I think the briefing dialogue could be sped up a little. There were times where it felt too patient. The background noise was nice - maybe include more of it? I know pilots won't be talking all the time, but just at the beginning/end would be good.
There were a couple of typos around the place - if you want them hunted down and listed just ask me.
Some sort of intro/ending movie would be nice. Maybe a very cut-down version of one of the trailers (fast scene changes with rapid black crossfades all set to some taiko drums) would be good - of course with a link to the team's homepage included at the end along with the BtRL logo.
The installation instructions were simple enough, but could it be made that installation of OpenAL was automatic, or at least prompted by default? When installing most commercial games, for example, the user is notified that 'now installing DirectX 9, click OK or Cancel'. Unless it causes problems to people who already have it, it would remove a slightly confusing decision for FS2 newbies.
Also, a desktop icon would be nice, for the newbies. Including a file named 'fs2_open' is confusing, given that you've publicised the fact that it does NOT require FS2 (so why is it on my computer? etc).
Nonetheless, very impressed