My longest killstreak is 20, probably from the jet in Paracel Storm.
Had my first real issue with the game last night. Played fine most of the night, quit a game to join someone else. Seemed like it took a little longer than usual to quit, but finally went back to Battlelog. Try to join the new server and it says my save file is corrupt and continuing will overwrite the previous save. I had no choice but to click OK. So it loads the new server, but it is windowed and all the annoying "tip popups" for new players are everywhere. So I go to video settings and set fullscreen and change everything back to what it was. Game goes black and unresponsive. Have to alt+ctrl+del and end the process. Then every time after that I try to join a game, it goes to a black screen and won't do anything. Sometimes I hear the loading music, but nothing on the screen and the loading music just keeps looping. I figured I messed something up in the video settings, so I edit the PROFSAVE_profile file and change fullscreen to 0. Now it opens up in windowed mode, but every time I try to click anything (deploy, weapons, etc...) the screen goes black and nothing happens.
Finally I decided to restart (again, as I had done it before) and now I can actually get into a game. All my vehicle loadouts are gone, and I keep getting the annoying popups, but I can play again. Not sure what happened, but it was frustrating.