Pandora is great! I use it all the time on my 15 min ride to and from work. Usually I'll listen to Siri at home. I plug my phone into the speakers (android phone) as I grew tired of the crappy internet player.
Pandora is simply a glorified jukebox. I've discovered a lot of new music from it. Might have 50 stations. But it is very limited. I find a lot of repetition of songs when listening to individual artist stations instead of quick mix. 6 skips an hour, 12 a day....that sucks, some but not that many streaming issues for me. My main problem is that frequently when I leave for work in morning it loads first song but often then buffers and skips it!!!! That's a common occurrence on my Infuse phone.
SIRI is all about content, content and more content!!!! I pay for Siri (Internet subscription), I don't for Pandora!! Both mainly used on my Infuse droid. The Siri app frequently drops or loses the signal and I have to pause n resume to get it back!! Slightly annoying as I'm usually right there to fix it, but would hate it if I'd left the room or changed seats.
I utilize and enjoy both, but I don't see them in the same light. With newer cars all having auxiliary ports on the radios, not sure why anyone with a smart phone would add a Siri radio if it didn't already come pre installed!! I've thought about getting a aux input installed on my wife's van so I can simply plug my phone into her radio and enjoy Siri!!!
To each their own, but I think it's completely wrong to compare Siri n Pandora. Thought about paying for P, don't know if I ever will. Been re-subscribed to Siri for awhile now.....enough said.