Yeah start with the latest I guess - uses more additional keyboards and effects than other albums previously but still maintains the sound that make Katatonia, Katatonia. Actually their ability to use the additional effects without drowning the music (like a lot of lame goth metal bands do) but rather enhance and mold into the music showcases just how brilliant the band is. I don't know what sort of music your into, but probably make DO one of the last albums you pick up not because it is clearly the weakest album rather because you might (or may not for that matter) take a while to get used to it, so good to get a feel for the overall Katatonia feel so you can appreciate it more easily when you do get it. Anyone of Brave Murder Day (usually comes with SoD EP), Viva Emptiness, Last Fair Deal Gone Done, The Great Cold Distance or Tonight's Decision are decent second albums.
Mikael from Opeth is the primary singer on Brave Murder Day, an album from 1996, when they were more of a heavier doom band - that's a great album to get but wouldn't represent their newest sound
True, but a lot of what you hear on DO, TD, LFDGD still bears many similarities with Brave Murder Day.
