For context, I've owned a J1A-S and J1TS-S but not a 2.0 J1A-GT. The GT shell I'm using currently is a J47-GT and I picked up a 2.2 J1A-GT as a possible replacement for it.
Some initial thoughts on the 2.2:
I love the collar. It looks and feels great up or down. I felt the previous iterations with the 3D collar ridge never sat right on my neck and felt awkward.
I like the hood better than the previous generation's ones. Combined with the collars I thought they had too much going on visually. I appreciate this version's simplicity. Unfortunately I have a big head so the hood fits a bit smaller than I'd like so I've removed it and auxzipped my J63A in because I love its hood.
The flak pocket is okay but I don't think I'll use it much personally. I feel like zipping the zipper from left to right should open the pocket instead of closing it. With how it is currently the zipper head blocks a bit of the opening on the left whereas if it was all the way on the right it'd be out of the way. I loved the centre pockets of the J1A-S and used them almost exclusively. You had the flak pocket quickly and easily accessible with the top flap, a sort of mezzanine pocket behind that accessed from the side and also another zipped security pocket behind that. I get that the security pocket probably had to go for the liner access to work nicely but can't help but wish there was still a mezzanine pocket behind the flak pocket. Edit: mezzanine pocket still present, thanks for pointing it out @RodG!
I like the new gravity pockets. They feel easier to insert and remove items from. I don't use them as intended with the wrist flick so I can't speak on that aspect but just as extra pockets I feel like they've improved. They sit more towards the back of your arms now instead of the side.
I still dislike the sleeve pocket. I get that it's a defining feature of the J1 but I've always found it cumbersome to use. I would've preferred the stacked detached sleeve pockets from the J16/J1TS on both sides but that's just me dreaming of my ideal ACR jacket.
I'm glad to have the articulated speedlock hem back in my life. Been missing it since I sold my J27. I think it's the best looking integration of speedlock.
I prefer jackets without interops because I don't often carry an additional bag, you lose the symmetry of having speedlock tabs on both sides and you sacrifice some backwards capacity if you have 2-directional waist pockets. This isn't so much of an issue for me with the J1A because I feel that asymmetry is intrinsic in its design and it's not lacking in the storage department.
Some small tweaks I'd make have to do with fastening the jacket. The centre snap is positioned nicely but I wish it was on webbing like the top snap so it'd be easier to grab at both sides with my index finger and thumb instead of having to get at it through just the right side with my thumb. Also I wish the two main zippers were detached at the bottom on both sides instead of one each for less fiddling around. I like how they're done like that on my J62-PB.
When it comes to Acronym jackets I prefer the simpler cuts with all the features I need/want. I go for my personal minimum maximum, if you will. I prefer my J47-GT over the J47A and J47TS I owned. I found their extra pockets surplus to my needs and unnatural to use. I value pocket capacity and accessibility over quantity. It's why the J28 isn't for me while most froth over it. It's why the J62 is fantastic to me despite only having 2 pockets. It's why the J16 is one of, if not my favourite jacket. Pretty much the entire front of it is storage space and all of it feels right to use. I feel like the 2.2 J1A-GT hits a sweet spot for me and overall I like the jacket a lot. It's not perfect but it's very good for me functionally and aesthetically. YMMV.