Ended up putting in just over 20 hours into this. Enjoyed it quite a lot overall. Random quick impressions/thoughts with poor formatting:
The map was fantastic, providing lots of cool arenas, and each mode was lots of fun on it. The gunplay's great, and I really like wide range of cross-class stuff that's going to be available. Loved popping roof campers with the XM25 and DMRs, and the boosted rocket speed is quite welcome. The UI is what it should've been in BF3, what with being able to click on the map for spawn points, and the minimap in general is far more readable. The sound continues to be fantastic of course, and after a couple patches, performance is fine on high on my aging PC.
For negatives, the netcode seemed like it's back to BF3 beta levels of jank. The delay on corner deaths wasn't as extreme, but probably a quarter of my deaths felt like a one-shot ordeals. Less annoying than the "I died after being behind cover for 2-3 seconds" nonsense, but still dumb. The UI is better, but there's still weirdness -- why is the text in the menu blurry? There's a weird quirk with the helo controls as well in that your controls lock up if you approach a 90° roll.
Finally, while all the weapons seemed good or at least decent, the Ultimax made me scratch my head. It's perfectly serviceable, but I don't know why you'd use it if you had another option. It doesn't provide the volume of fire of a belt-fed LMG, and it's not as accurate or maneuverable as a carbine. I don't know what role it's supposed to fill other than the "grind through this to get something better" niche.
Anyway, yeah, it's not without it's flaws, but it seems like a great game overall. Gonna be a long two weeks.