I think he did the right thing, the story was like he said "seemed like just filler". We never like to see things we enjoy end but Kirkman did the Walking Dead a solid on this exit. Everything was wrapped up tight and all the bases covered. I would have liked to see the "old man" Negan but I think he did that on purpose for the reader's imagination.
The issue had me feeling satisfied like at the end of some movies where they tell you what happened to the characters after the curtain closes.
I've been reading TWD on and off pretty much since it began. I only just caught up to where Rick was shot so I really only had to wait for the last 2 issues.
I think it ended in a good way. It was funny as I didn't realize until the last page that I was reading the final issue, but for most of it, I felt that this was a fitting ending (for me at least to put the series down). It wasn't like I was dissatisfied with it, just that it had run it's course. I didn't need to find out what happened next (kinda like in the TV series where in my experience, the show ended with Carl revealing he was bit.)
The story had been told and anything more would have been a rehash of an existing story arc. We got the closure.
The only thing I would have changed would be hearing Negan mumbling"****ity****ity************" at Lucille's grave.