...Poorly? Spoilers ahead.
Man. I've really been enjoying this series despite some uneven bits here and there, but that just was not a satisfying ending at all, in my opinion.
The first nine issues have built up The Five as this force that has just steamrolled over the entire galaxy, taking over planet after planet with little to no opposition. You've got a sentient computer program, a consciousness that can inhabit multiple bodies at once, and can take over new bodies at will, a reality warper who is essentially a god (if she's able to concentrate), a brilliant, scheming double agent who betrayed the League... And Kali. Who has six arms, I guess. They've been built up as this unstoppable force that the Justice League is ill-equipped to fight, especially since they still haven't really "become" the Justice League proper yet, since the cloning came out wrong.
I guess I didn't assume that "the defeat of the five" was going to be a reasonable goal any time soon. In fact, when issue five basically ended with the League escaping from the Five, I figured we were going to put that arc on the backburner for a while (until the last page said that issue ten would be the conclusion, a bit of a headscratcher), and we'd see the League's further adventures, this time on their own, no longer backed by the now-Five-controlled CADMUS. I figured we'd get a few arcs of the Justice League as galactic fugitives, continuing to show them become more and more like the heroes they were cloned from (which, mind you, has been the ultimate arc so long), and then eventually, like another ten or twelve issues from now, we'd see them return to The Five, fight them, and somehow win since they were actually the proper Justice League again, or had at least become more of a team.
Now, granted, we do get a bit of the "they're actually fighting like a team now" stuff in this issue. That part is good. This issue isn't horrible or anything, the art continues to be quite good, some of the writing is pretty snappy, I liked the idea of a futuristic Camelot planet (which we'll apparently be returning to next issue), and I think making Teri the new Flash is a fun idea which is paying off well. The contrast between her and her brother, and the parts where she talks about how she still wouldn't hurt him (even though he murdered her a few issues earlier) is well done.
That said, MAN. MAN. How did these guys take over the galaxy? For one thing, while the idea of bringing them to a deserted planet to take out The Convert and Coeval right of the bat is interesting, I thought they had implied that The Convert's whole thing was being a consciousness in multiple bodies at once— I didn't realize there was some sort of range on that. This "victory" seems hollow, since I had thought there'd still be thousands or millions of Convert bodies back on Cadmusworld, or something. Similarly for Coeval, he says just one issue earlier that, as a program, he can be everywhere at once. Severing him from technology seems... Like an odd way to defeat him.
Kali is pretty easily defeated, and she always seemed like the least threatening of the five (even if Terry is less physically imposing, he's at least smart— unlike Kali). Terry is also taken out pretty quickly, since he really had no business going in the first place— even if he's genetically enhanced somehow, which I don't think they ever said, he's not on the level of the League or the other Five members in a fight. It was an odd, stupid decision in the first place. That just left Locus, who was quickly outwitted (again) by Green Lantern. Seeing GL create what seemed to be a fully sentient construct was cool, but reality warpers being beaten in an outright fight is always weird to me, since their power levels are so far beyond that. Granted, Locus isn't exactly the smartest one out there (in fact, her characterization came to bother me by the end of this arc for a whole other reason, but I won't get into that now).
Basically, the League wound up curb stomping the Five so hard in this issue, it really pulled me out of it. These are the guys who took over the galaxy so swiftly and decisively? The Convert was literally foiled by Batman macing him. Like, literally. Batman says he's using mace on the convert, to prevent him from jumping into anyone else.
The problem is, The Five were made to be these ultimately powerful beings, to the point where the only way they could be defeated was by idiocy, charging in without a plan, and without backup, and being just mercilessly beaten by the League. That's not a satisfying resolution. An issue ago, everything seemed hopeless, and now suddenly they were taken out with ease.
I still enjoyed the first ten issues of JL3K, and I'm interested to see what they have next, but this conclusion rang really hollow for me.