It personally wasn't anything huge. Lighting changes, better first person viewmodels, particles system. Aside from that, not much has changed. The menu music is atrocious and the team preview screen feels mostly just as a way to show off cosmetics more.
I don't feel like this has any right to be called "counter strike 2" when this all could have simply been released as an update to the game it still is at its heart: CSGO.
I played one while match and asked myself "This is it?" And promptly exited the game. Nothing has really been added to bring players like me back. Also the matchmaking feels super intense, I was getting canned alot more frequently than I was 2 months ago in the previous version of the game.
It also has really really bad Frame stutters that I couldn't figure out for the life of me, and a game looking as bad as CS2 does has no right to behave in this way. My friend also noticed this too.
Overall, cool I guess, it's just a big CSGO update, that's all it is; valves attempt to keep Counter Strike alive for another 10 years.