A horrible mess on every level that pretty much spelled the end of the classic Marvel Universe.

Of course, your mileage may vary.

Good analysis. I'm having a hard time recalling a storyline in the modern era that impacted the Marvel Universe as much as the Onslaught storyline did. I guess possibly the recent Secret Wars series did, but the thing that separates the two was the way the Onslaught storyline slowly unfolded over the course of time in many titles.
I remember there was a lot of genuine excitement over Onslaught as fans speculated on what was happening and who Onslaught was. I just don't think there's ever been anything like it.

I guess it was a way to reset those books without doing a crisis type book. As it was pointed out already, it ended up having top tier creators doing the affected books once it was over.  With the exception of FF, the books that were canceled were bad.

I was big-time into the X-books, but not the rest of the MU, at the time. Looking at it from that standpoint, it was a mess of a story that really hastened the end of my love for the X-titles (although the completionist in me kept getting them for years afterward).

As others have written, though, it was a boon to the rest of the line, which was struggling horribly for the most part (having read Thor up through issue #502 in the past couple of years, I can vouch for at least that book being crap). After the alternate universe stuff ended and Heroes Return, they had top creators working those titles and putting out quality work.

It was the start of the cycle of events and new #1's, the trend that defines Marvel these days. It started here and has snowballed over the years so that all Marvel is these days is one event after another with new #1s for books with each event. It is, in terms of business model, the start of modern Marvel.

As a story, it was all hype and no delivery, overwrought angst and change for the sake of change without an actual story to tell as its driving force. It was marketing determining story rather than the other way around.

-M

Onslaught was the book that broke my Marvel habit. When I finished university and was making enough, I finally did something wanted to do as a kid, get every Marvel book that came out each month. With Onslaught, that ended. In hindsight, it should have never started or at least ended sooner, but I was young and foolish. I went form buying the entire Marvel line to 2-3 books (Busiek's T-Bolts, Ostrander's Heroes for Hire and Waid's Ka-Zar are all I was getting at that point I think-I may have been getting Daredevil too). My lcs owner hated, because I was not the only one of his customers to do essentially the same thing-tap out on Marvel.

With Heroes return I picked up a few more books (Busiek's Avengers and Iron Man, Waid's Cap), but I had dropped the other Marvel stuff I was reading at that point. But the days of my fandom, where I made mine Marvel, right or wrong, where the brand was the thing, were done. I realized that the books I had been enjoying the most, despite buying all that Marvel, were from other publishers and now I had money to explore a lot of things in comics I had previously forgotten. It was also the point where I stopped filling in my Silver/Bronze Age runs of Marvels (2 short of completing Avengers, 2 short of completing Strange Tales/Dr. Strange, TOS complete from 57-up, Cap complete from 100-up, Iron Man complete from 1-up and Hulk, Thor and FF in process) and led to me selling them all off a few years later.

So no I didn't like it, and what it represented for me was the death knell of my Marvel fandom. I still enjoy form stuff form Marvel, but I no longer seek out stuff because it's Marvel.

-M

It also led to alot of great runs right after it... Busiek's Avengers for instance... Thor and Iron Man both improved greatly too, though I'm not sure exactly which runs came right after.. I think Quesada for Iron Man and maybe Jurgens for Thor?  or Straczinski?