Design, copy editing, and agate are generally the main desk duties. At the places I worked at, there was also a decent amount of writing non-rev college/prep roundups from press releases and call-ins.
As far as the schedule goes, the hours are certainly more steady, but be warned that leaving work at 1 a.m. every night and having to work nights on most weekends is no way to have a social life. When I was first starting out, I lived with my best friend for a couple years, and most days the only time I saw him was when I was leaving to go to work while he was coming in from work. It was especially tough around holidays, when most of the staff was home since there are no games going on, but I and a couple other deskers were still in the office to put out the paper. So depending on what stage of your life you're in and what your friends' and family's schedules are, that could be a severe downside.
And what Frank says about adrenaline is true. When I first started on desk, I tried to get to bed by about 2 a.m. every night. By the time I got out of the biz, I was going to bed at 6 a.m., and I did spend a lot of time thinking about upcoming special sections and the like (though I suppose you don't HAVE to take work home).