And I actually love both Road Salts as well. They're not up to par and hardly comparable with the first five, because of the huge difference in style, but they're very good and clearly Pain of Salvation as well.
Remedy Lane is generally considered their best, like Adami says. I have a soft spot for One Hour by the Concrete Lake and BE. The Perfect Element is amazing and Entropia is one of the best debut albums in progressive metal ever.Pain of Salvation has an amazing discography and I consider this album to be a dud, even though the live renditions of the album tracks on 'On the Two Deaths Of' (their live DVD) are really good too.
Hell, they even redeemed their worst song (MMMM, in my opinion), with the acoustic arrangement on Falling Home. Makes it way better and more open. There's just something about the general vibe on this album that I (and others with me) dislike for some reason, despite it not being especially bad or anything.