For the most part, I like where DoI has gone. It certainly needs more solid teamwork (compared to Insurgency) to get a quality play session, or sometimes even a win. The coop mission types work well, the maps are nicely done (though some objectives can be a touch close), and a good sense of atmosphere.
Last night was my first play with the release build, so I can't really say anything other than I need another few sessions. As Rhino mentions, the weapons have been rebalanced. The SMG types seem to be a bit less effective, and the rifles more so. I carried a WW1 bolt action rifle last night out of necessity to have that role in our group (a rifle I typically avoid), and was surprised to find myself doing quite well with it. I played that weapon the rest of the session, working from the mid-field, and landing good single shot kills. Still, I do understand complaints against this type of weapon balancing, since the AI taking what should be serious hits and still performing at 100% is annoying.
And the AI is my biggest sense of frustration in DOI. This is not new with the release version, either. All through development the AI have tended to be far and away too accurate, IMO. I could deal with this accuracy if they weren't behaving as they do, running with a bolt action rifle and firing it with greater accuracy than my rifle which is rested on a window ledge. If instead the AI would take a knee and fire (preferably from behind cover, crates, etc), OK that kind of accuracy is fine because that's what a player (or even real life) would likely want to do. Plus the AI having to move to a position to take that knee, gives a bit of precious time to get a shot or two in before they nail me. Similarly when I've got a heavy MG on a window or ledge and rain down an alley of fire, the AI will just dance in it and nail me with a rifle shot, of course while they are standing/running. Counter to all I've read and seen outside of PC shooters.
But this is something probably well beyond the level of AI that the developers have to work with, in the first place. They were designed for run-and-gun shooting.
As it is, though, I'm reminded of those types of games that seem to be designed around the notion that excessive difficulty is realism. I don't always agree with this idea, and this a big part of why I am completely happy to step the AI difficulty down a notch to improve playability and most importantly, reduce or hopefully eliminate the sense of frustration, to keep players interested.
As to the server and connection, I have zero complaints. Performance has been perfect from what I can see, and while my ping is higher, well that's just some ISP thing on my end because others don't have this issue. I can play past the ping in both DOI and INS, so all thumbs up on that point.