It's a great book. It's full of fluffy stuff and crammed with flavor. The models ooze cool, and the army is looking really fun to play. It's incredibly deadly on offense, but they're paper tigers (just as they should be). Their bombers and fighters have some crazy cool rules, but they're still only AV11, so they'll still be brought down by autocannons and whatnot. Lelith is a pretty good combat character (not as good as she's been wanked to be, do the math with her S3), but she's still only T3. Hit her with a S6 something and she goes splat all over the battlefield. Pretty much everything in the codex is like that except for Grotesques and Wracks (who big deal is being harder to kill).
The Power form Pain rule will be interesting to see in action. It is a little limited as to how to get them, so they won't exactly be everywhere, but it definitely means that DE units will be getting stronger as the game goes on. It's an interesting effect and changes how you have to play against them, which is a good thing. Overall, the book looks well balanced, though of course we haven't had the time for the "optimal" army build to come out.
