Ive started using the new Yahoo search marketing system and think overall its a big improvement over the prior setup. Its more like Googles adwords program, just not as good or without all the traffic!
The one thing I did notice though is that they don’t automatically set any daily limits for your different campaigns and in some cases the adjustments of keywords and bids can indeed drive more traffic but at a high cost and if you dont have any daily limits setup, you can pay a lot more money then you might want to.
Overall its a better system and I would suggest anyone who is going pay per click advertising use both Google adwords and Yahoo search marketing.