I find that they play the same songs again and again...I have a rat pack station, and every time I start it it plays either, " Boys Night OUt" or some song with Venice in the title...
Pandora needs some new material
I find it helpful to add other songs or artists to my custom station, as well as rating each song that comes on with a thumbs up or thumbs down. That way Pandora gets a feel for what I like and don't like and over time is able to provide a wide range of the music I enjoy, even stuff that I've never heard before but still end up liking.
I used the Directv app for the first time today, while not as great as it is on my media center PC, phone, tablet, smart tv, BD player etc, (the popping between songs was VERY annoying), it was still better than the music channels I pay for with my DTV subscription.