First I would like to start of by saying I am generally happy with Pandora and have been a member for many years, but... there are things that defy my understanding given the amount of research Pandora has performed on music
I do not have a high level of understanding of music theory, but I try to tune my stations to a 'sound' (whatever that translates into in music theory). I always reach a critical mass of number of 'thumbed-up' tracks on a station where I seem to just stop receiving new relevant, applicable music selections. This critical mass seems way too small given the total population of songs in the Pandora library. I am just not convinced that I found them all - not by a long shot
I also get sent massive numbers of song suggestions that are in no way, shape, or form relevant to the station in question. The ratio tends to be 20-1 to 30-1 some days, and this seems odd given the amount of data Pandora presumably has on music. In some cases, I will need to thumbs-down every available song by a given artist or album before they stop getting sent to my station
Also, just because I have a prog-rock station does not mean I want prog-rock suggestions for my electronic station
I have seen and participated in a number of posts related to these topics, so they seem to be somewhat widespread with no clear global solution. This is all meant to be constructive for future development, but I would be interested in any feedback on the topic