I saw them for the first time in concert last night, and I can say is WOW... they easily blew away over half of the concerts I've seen, including some of Journey's. In fact, it probably ranks in the top five of concerts I've been to.
If you're not familiar with Polyphonic Spree, it's a symphonic rock band. Best way to describe them is ELO-squared - besides the string instruments, they also bring in a horn section and choir (however, the lead singer is no Jeff Lynne).
This is probably its best-known song: http://youtube.com/watch?v=jQAvflPexng (you may remember it from "Scrubs," if you are a fan).
If you view any of their other songs on YouTube, including the covers of Nirvana's "Lithium" and McCartney's "Live and Let Die," just be warned - YouTube does not do this band a grain of justice. You have to see them to believe it. I have never, ever seen so much energy in one room in my entire life.
If they ever come around your way, consider seeing the band, if just for once - the tickets are still cheap enough that it won't hurt too much if you don't like the show. I've yet to meet a person who's seen the Spree lives and hates the band.