I just binged all of KHR within the span of a few weeks! And good god, this manga really doesn't fail to make me fall in love with it. This was my first time making it all the way to the end( i grew up watching the anime as it was airing tho ), and it's really sad, since it does seem like there was a bit of rushing. Granted, however, that a lot of the pacing in general is really fast. Does that make it inherently worse? No, I don't think so. While giving little things more time to be fleshed out would have been nice, you do have to sit and think of what JUMP is like as a publisher, and how KHR was never some super huge phenomenon like other JUMP manga.
It had to put in extra work to even TRY to keep up with things like Naruto, Bleach, Gintama, and One Piece, so action was put at the forefront of most of the arcs. Fights, battles, so on and so forth. All so that it could hold the attention of the readers. Not to mention the ending was rushed simply because KHR was CANCELLED. It was given it's death date, and Amano-sensei had to work within what she was given. There was no hope of a 100% satisfying ending when you're suddenly told by your editor that the manga you've spent the last 8 years writing and drawing is going to end in a certain amount of weeks/chapters, and there was nothing you could do about it.
Manga aren't given 100+ chapter warnings that they're going to be canned. More often than not, they're given maybe a few weeks of notice, and then forced to work as fast as they can to cram in everything they wanted to just so that the author could have some semblance of an ending that wasn't a complete cliffhanger.