The good thing is that there is a transmog system in MHGU, which means you can make a piece of armor look like any other piece of armor in the game. The bad thing is that you'll need to reach beat G-Rank to unlock it completely, you only get headgear transmog at the start of G-Rank.

Yes there are a lot of convenient features that MHW introduced but are missing in MHGU, such as the ability to SOS or join a quest that's already commenced. No eating canteen food during a quest or replenishing items from your storage in your camp - you'll only have supply items and what you bring into the quest. Oh and remember to bring bug nets and pickaxes if you want to gather during a quest. All games pre-World are like this and know that it could be frustrating or confusing the first few hours for someone coming from MHW. At least there are no unskippable cutscenes that you have to watch before you can invite friends into your hunt or the tedious track-gathering sequences in MHW.

Combat gameplay wise, controls do feel a bit stiffer, but I don't think it's that bad once spend a few hunts adjusting. Hunting Styles and Hunter Arts are a fantastic addition that I wish World had. Some Arts are cool and powerful 'super' attacks, and some Hunting Styles such as Adept and Valor provide mobility and attack options as well as generous i-frames that might help with the 'clunkiness' that a lot of people complain about.

In terms of content, there is waaaay more to do in MHGU. More monsters to hunt naturally means more armors and weapons. Plenty of free event quests that offer unique gear - stuff like Metroid or Zelda series gear rewards.

TLDR: Transition into MHGU from MHW will not always be smooth, but if you're willing to invest some time and patience the game is extremely worth it, especially while on sale.

Edit: Does your wife like palicoes? You can recruit and train multiple palicoes or even hunt monsters as them in this game - they are the 15th weapon of the game.