First of all, since I bought Civ 5 vanilla, the game has always been very problematic for me in MP. Both vanilla and G&K, when it came out, were prone to crashes, freezes, problems with loading saved games, etc. etc. I say it for proper context.
Yesterday I played a test game with a friend. Two people and a bunch of AI, so far. But:
- turn times are VASTLY better now on my computer;
- no crashes for almost 200 turns, when we finished for the day;
- no disconnects, no problems or glitches of any kind;
- saved games load properly, which had hardly been the case before (we tested the save we made after we finished playing);
- another friend, who could not play MP for some unknown reason (the game would always crash) now experiences no problems whatsoever;
- Hybrid mode works correctly, as far as we could tell;
- disconnecting and reconnecting does not cause any problems, and is actually pretty fast. You are not taken to a loading screen when someone reconnects, the game is merely paused. So it's possible to look at the map while waiting. I haven't tested if city screens, tech tree etc. work properly when waiting for the player to reconnect. That's among the next things I'm going to check.
All in all, the game seems to work near-perfectly, especially compared to the awful performance before.
Soon I am going to try out if the game works smoothly for a larger number of players and/or AI. I'll post when this happens.