Now I am level 13, and I noticed the monsters that are my same level (with magic) are a pain, such as Storm Queen Harpies, and Centaur Kolkar Stomers or whatever. I usually am doing quests around crossroads/ barrens, and usually with a healer type. I really am enjoying this game, I wish the character I have right now could be retail, but beta is just beta, you test, and then get deleted! :D, aw well.
Whoever else got into the stress test, unless they're on a bad server, would agree, there is no lag. I got NO lag so far. NONE. And this is a stress test? Pretty stable ;).