Yeah it's a real pain where I felt like a paper tiger while I was leveling. When it's only one or two enemies it's ok. But you get overwhelmed quickly if you are not careful. Without using a healer at the same time, you just die a lot unless you really pay attention to the amount of mobs in the area as well as their strength level. For the most part though, outside of Heroic areas it wasn't bad as long as my gear was updated. When I died a lot is when I didn't notice my gear was 10 levels out of date