Since it won't be showing up in my May favorites I'll give you my basic feeling towards the first issue of the series thus far: meh. Spoilers ahead.
I didn't dislike it but I wasn't exactly wowed either. Parts I like and parts I didn't like. What did I like? I thought it was interesting to see the Justice League and Green Lanterns investigating Orions apparent death. Plus Dan Turpin showing up was cool. Libra is generally interesting character and he has this aura about him that makes him kind of cool. Plus the JG Jones art. Good stuff.
That said... I didn't care for the Monitor scenes. It's not that i couldn't follow them. No, I didn't read Countdown but the scene generally explained what was happening but I just didn't get into it. It was weird to see the JLA talking of the New Gods as if they had little interaction with them. Plus the death of Martian Manhunter was kind of anti-climatic. On hand, it served a point. To show how dangerous Libra could be by taking down of the JLA's top hitters but... it's the Martian Manhunter, he deserved a more heroic death.
At the end of the issue I wasn't impressed. Rereading the book I did pick up extra tidbits and some of the symbolism, as described on message boards, shows Morrison does put a lot of details in his work(despite his haters claiming the contrary.). I'm sure Morrison has a plan and I'm going to keep buying for a while because I believe in him. But this was just an okay first issue.