Of course the season pass for Deus Ex is rather expensive. And the main two "dlc's" that are coming out several months in the future.. get put into the middle of the Deus Ex game. So, you'll have to replay the game for them to make sense.
At least, that's what it seems to read like from the info they've given so far.
Oh yes, plus the season pass gives a bunch of in-game gubbins like extra money, praxis points, parts for weapon mods, and stuff for the alternate game version that you can do with Deus Ex.
Which does tend to make you shake your head over the whole thing. At least to me it does.