The biggest problem with garrisons I've noticed (fixable easily)
There is little filtering of the missions list! You get a ton of them to choose from and it's exceptionally difficult to filter out what you have, what you have seen, what you may want to have available (based on attributes of those missions etc.).
At least you do not get to lose the scrolling position if you get back to it!
Can't post links yet, but search for Compact Garrison Mission UI, it's on curseforge, and has a topic here on MMOC too. You can't filter, but you can see easier what missions you can do.
Doesn't seem like there's that much to me. I don't see any need for filters at all but I guess it wouldn't hurt. It's an incredibly simplistic and easy to read system and there's really not THAT much to 'filter' through.