I like that we can see what our competitors are bidding for so its easy when i'm looking at an auction or in my dashboard if someone is trying hard not too spend more than me! Sometimes you have no idea who's winning but there could be information available somewhere else which would help us out as well!! So far nothing really - just minor things such as some of your ads being displayed over other ones etc..
We're hoping this will get better once Google starts rolling theirs into Adwords themselves soonish ;).