I leveled Affliction all the way through. I can't speak for other specs since I never tried them. I found no issues keeping myself alive other than the times when I bit off more than i could chew through a foolish pull. I was also able to solo a lot if not most of the elite quests. Rarely had any down time.
My build is in my
armory page if you want a reference
Edit: Affliction is probably not the way to go if you are looking to PVP. There is almost no burst damage.
Edited, Feb 23rd 2009 1:40pm by Aniclator