First off, I have to say that while I enjoyed the first eight issues of Justice League Dark, this first issue with Jeff Lemire as writer seemed to be so much better. I think I'm going to enjoy Lemire run on this book.
Having the team get together under the auspices of Steve Trevor and A.R.G.U.S. seems to be a stronger reason than the team has had to be together up to now. I'm assuming that Trevor is going to offer other deals such as the one he offered to Constantine this issue as the reason why they get together for other missions. It was also nice to see the name on the cover finally used this issue. It was a nice touch to have Trevor mention that it's the nickname that A.R.G.U.S. has for them.
As for the story itself, I've always like Felix Faust and the new cult and creatures he controls are fairly horrific. That combined with the power up from his new found toy and he comes across as a real threat now. Speaking of that toy, I'm intrigued, the name the Map to the Books of Magic suggests some things. Could it include a possible appearance by Tim Hunter maybe?