So I watched the Mobile Suit Gundam movies, as well as Z Gundam A New Translation.
The MSG ones did a good job of hitting most of the important points of the series without relying on having previously watching the full series, while managing to cut out some fluff. I still enjoyed watching them.
A New Translation, on the other hand, felt kinda disjointed at times. There was parts that I felt like I wouldn't have known what was going on if I hadn't seen the series previously. This kinda also worked against me, since I felt like a lot of important stuff was left out. Then there was the new footage, which was just... jarring next to the old stuff, particularly in the latter movies.
I suspect that if ANT had a longer running time like the MSG movies did, it might have helped quite a bit. It would have given more time for stuff to be fleshed out, like the various meetings with Four for example. The new ending... I'm not sure how to feel about it. It kinda has a lot of repercussions that might never get addressed.