well what is good about them? They are sooo mediocre. They aren't innovative, Original, progressive or intelligent. They have influenced a whole lot of shitty bands that polute rock radio stations e.g Puddle of Mudd, Creed, Nickleback etc etc. you may say this isn't their fault they were before them but I say that makes it worse!!!!
Eddie Vedder has one of the worst voices in rock (in my opinion) and again, this has influenced alot of crappy american bands to immitate him.
I just think they are middle of the road rubbish and do not offer anything interesting or special to rock/metal in general.
They are just the very defination of the corporate rock sound in my eyes and I don't really understand what an Opeth fan would find good about them as these two bands are at the opposite end of the spectrum. Opeth are very intelligent with their song writing, have a one of a kind sound, are genre defining and produce quality album after quality album. None of this can be said for Pearl Jam...
Of course this is just my opinion, I just find it very strange that there are so many Pearl Jam fans in an Opeth forum, wouldn't have picked it.