I really did like it, but they failed to expand on the system and put an end to it with the epic lair. What was needed were additional activities and objectives, possible new modes of play in the other zones even.
Love the game, but the trend in this game and CoH seemed to be releasing something, tantalizing with the prospect of expansion, then completely disappointing in that.
I think what separates CO from CoH is that, CoH did not focus on end games, and was more variety focused. It'd continue old stories every so often, but when you look at things like the Rikti War Zone, or Cimerora, you notice that the stories were designed to allow for newer stories. Hell, even earlier issues preceeding Issue 10(Invasion), hinted that the rikti would come back for round 2. In the case of the Cimerorans, the story focused on what the 5th column was doing since they got their butts kicked by the Council. The thing though, no matter what the content, be it earlier game, mid game, late game or even "end game"(which was not CoX's focus, even with incarnate content), CoX had multiple stories to tell and they often lead to other stories.
In a way, though, CoX had enough updates that you saw a lot of improvement in the writing. In a way, it wasn't so much as trying to achieve perfection, though, as it was going for the highest levels of refinement it could. It's developers were like blacksmiths in medieval times; they were always refining and experimenting with their work.
The other difference CoX has to CO, is that CoX didn't try to twist things into something half done. If it did, it was never intentional, was rare, and the devs would return to fix/finish it. CO always did so intentionally. The rampages were done for a need for end game content that the devs were hopeful enough people would play. Because people stopped playing the rampages, and players had asked endlessly for the ability to make and play a villain, well, the devs had a "AHA!" moment. The "AHA!" moment was to make players play raid bosses. Not let them make their own villains as they asked, but play pre-made raid bosses. When popularity faded within record time again as I predicted(in zone chat no less), they decided to make a new lair at the request of try hards. Of course, I'm sure it's dying in popularity to with how repetitive it has to be, especially since I read people use trinity teams in it, to, and how punishing it is(that is, every single player has to be perfect in the puzzles).
CoX refined it's stuff. CO never refines anything. CO instead changes on a whim to try and pander to players with a narrow view of how games should be played, OR it tries to half-ass everything. It's in a constant state of doing the minimum, instead of going for the gold medals.