In single player mode, all you have is your follower, and any summoned companions on the top-left hand-side of the screen. It's easy to see(as it should be) your followers level no-matter if you're in single player or co-op.
This patch I've been playing a lot more single player than I have been co-op, and I had trouble finding my character level since there is no avatar on the top left to tell me. It took me awhile to find it, but I eventually found it (top right of your helm in your inventory). It's tiny little white font, not the easiest thing in the world to see or to locate.
In D1, D2, WoW, finding your current level was easy. In D3 (single-player), I just think it's a little hidden. Especially compared to previous blizzard titles.
Can we get our toons avatar on the top-left hand-side of the screen at all times? No matter what mode we play.