I'm starting to see this on Pandora.
I listen to it nearly constantly at work (I usually end up paying a $1 a month to keep listening), but the ads are starting to get out of control. It doesn't help that there is a very limited selection, and maybe as a result they seem totally untargetted. It's irritating to be listening to trace music while I work, and then cut to a commercial for Ford trucks with country rock playing.
Also, I was trying to use it at home this weekend, and while trying to change stations I was interrupted by video ads.
I guess on the bright side, the ads are "high quality", for mainstream products you might see on TV or radio.