Admittedly I just skimmed what has been posted but I will put in a couple of my opinions:
Coming into the game having never played X-Com, there definitely needs to be more of a tutorial. This is a wonderful game and can stand on its own without a direct comparison (or necessity of) having played X-com. What is intuitive for X-Com vets comes at a steep learning curve for newbies like myself.
Going 3D - tough one. I'm old school and like the current look. That said maybe even just going to a "90ยบ-4x rotation" style to get better camera angles which get a little wonky sometimes would be nice.
Air-combat - I like the radar style look to it, which also adds to the "fighting from a command center" feel-kinda reminds me of the old missile defense game. Any major changes I think would be in going into 3D as well which by extension is starting to get well away from the overall sense of what the game is.
RnD - I did read another comment on buildable/unique weapons which I think is cool. Let me see if i can piece together some new kind splatter gun - or maybe have it blow up my lab
It would be nice to customize some uniforms by color/base style. I would like to be able to have badges/insignias to specify which of my bases a soldier at least started at. Also maybe officer/rank difference in appearance.
UI - tutorial would help this. I have no problem with the mechanics or functionality
Modding - n/a for me. Although i do want to learn how to build an implement mods myself
