For AdCenter not working right: - Approval system/process is horrible when ads get stuck for no obvious reason. For example, you have a few ad groups in a campaign and some ads get approved right away while other wait forever while carrying same or almost same text. - Conversion, at least in my case, is not as good as it used to be (prior big merge).
Support: - Again approval in which support folks always give an impression they don't even look into the account, yet are full of words that justify the situation, instead of simply fixing it. For example, they find you have TM term in the ad text and catch for that as a main reason while ignoring the fact that same terms went just fine in other ads that went approved right away. They just keep telling you stories that make your hair go up.
Just these days I had a case with new markets as Yahoo is stopping service in some European countries. Some ads got stuck and they kept telling me how I would have to wait because those were new markets, but I had bunch of other ads for same new markets created back in August that went approved almost immediately. And they kept ignoring such facts. Well, I can afford to pause everything. It even makes my life easier as I don't have to look into paid search expense on AdCenter side. Gosh, those companies instead of helping clients help them ditch the service.