I'm kind of torn on this issue. I'm really quite amused that Geoff Johns is going full-throttle on his Superboy Prime as an angry fanboy thing, but at the same time, not much actually happens here. The issue opens with Superboy Prime (who lives in "our" world) reading Adventure Comics #4 and complaining that he has been included in the Blackest Night crossover. That type of in your face fourth wall breaking is hard to come by, and seeing SBP rage at his local comic store is pretty funny. He's even reduced to scouring the internet for clues about what happens in issue 5. Unfortunately, Alex Luthor gets a black lantern ring and pops off to Earth Prime to rile up SBP and eat his heart. Alex has some great lines, the best ones being dead-on statements about what the fan community thinks about SBP. I also liked his observation about computers, that they are instruments that we use to "channel our rage." It's all a bit on the nose, but like I said, it is amusing. However, not much actually happens here. I do think this was worth picking up just for that sweet Blue Lantern ring though!
I'm confused on the Legion. Brainiac 5 and the Legion are shown in the main story to be in the process of excavating old comics that they can use to try and determine what happened hundreds of years ago. Brainy also mentions that Sun Boy and Element Lad are dead. Didn't I just read about Sun Boy last month, or am I misremembering? It also seems like the status quo is quite different in the backup story. I'm totally befuddled as to the timeline and what is happening. I must confess that I haven't read Legion of 3 Worlds though, maybe that clears it up.
Jerry Ordway is spot on, as always. He's got such a great blend of emotion and action in his pencils that I always love it when he gets to headline a book. Clayton Henry has a clean style that works great for super-stories too; his Dawnstar in particular is quite nice.