Sucked in. That's what I am. I just finished Disc 3 of Season 2, and I'm halfway through Disc 4 (with the SHOCKING, yes SHOCKING post-Super Bowl episode, complete with gratuitous shots of Jennifer Garner in very, ah, revealing lingerie). It's an interesting series - it keeps me guessing at its twists and turns, makes me salivate for the next disc... but I'm not sure I'd spend actual money to buy it.
I think the problem is that the episodes just flow one into the other - its a big 16+ hour arc, and popping in one individual episode seems like it would be nigh-on impossible. Whereas Buffy and Angel tend to be comprised of individual episodes that tend to have satisfying beginnings, middles, and ends, even if they are part of a larger arc. You can pop in Calvary or Touched individually, even though they are very arc-centric episodes, and not necessarily have to worry about watching three episodes on either side to make the arciness more complete.
( Spoilers through The Double Agent, 2x14 )