This final issue is my least favorite installment of the series.
It's to be expected, I guess. Endings are always harder than beginnings, and while the other three issues played with past highlights (and lowlights -- i.e. the Clone Saga) from the Marvel Universe, this one deals with the almost-present-day Marvel U. It's Spider-Man and the X-Men as they almost are now, with a post-Brand New Day Spidey and a pre-end-of-Whedon's "Astonishing X-Men" team of mutants.
So what's missing from this issue is Christos Gage's witty perspective on the past, and Mario Alberti's enchanting images of nostalgia. Instead, we get Gage writing about Spider-Man teaming up with the X-Men yet again, and Alberti's take on the current look of most of the characters. And Alberti's work looks a bit rushed in this finale as well -- it's not as blindingly great as it was on the previous three issues.
Even if "X-Men/Spider-Man" #4 doesn't quite end as well as it began (and it doesn't), it still manages to be a nice little four-issue overview of the ever-changing, yet almost completely stagnant Marvel Universe. Cyclops even comments on it here, describing how much has changed, and Spider-Man agrees, until he realizes that he's pretty much doing the same stuff he was doing years and years ago. It's a nice little wink at the Brand New Day status quo, but it's also a comment on the nature of this fictional universe.
This issue wraps up the Mr. Sinister overarching storyline, with a cloned Kraven the Hunter (Xraven, as he's called here, for reasons that will become obvious once you see him in action) on an anti-mutant urban safari. Xraven the Mutant Hunter may never appear again, but Alberti gives him a nice, menacing look, and Gage gives him just enough personality to give him a chance to stick. Will we see more of Xraven? Will Marvel's Mighty Fans demand it? I doubt it. But it's possible.
This four-issue romp through the Marvel timeline was a bit too conservative in the end, with the walls of continuity preventing it from becoming little more than a history lesson on various superhero eras, but thanks to Alberti's artwork, it danced around within those walls with glee.
"X-Men/Spider-Man" probably doesn't mean anything in the long run. It won't set the stage for any major events, and it won't change the way you look at these characters, but as a celebration of its protagonists, it worked quite well. And even with Alberti's slight drop in quality on the final issue, it still looks better than most other Marvel comics on the stands in the past year.
And it was fun while it lasted.