While people complain about no single player for this game, I do not care as I heard it will be released after Multiplayer has been patched properly as it is the main focus on Arma games.
The game itself is Beautiful, The lighting is great, Player textures are awesome and the animations are less clunky compared to Arma 2 and make a more enjoyable experience for the player.
There are some lag issues online but that is due to what server you are connecting to, some server host have weak connections causing lag for al players. I recommend Sa Matra or Seal Team Sloth servers.
The best thing about this game is the community has already put alot of work in, with 100's of mods released from texture packs, to added weapons and vehicles/air craft all the way to sounds packs and realism healing/revival. 1000 or so custom missions made by the community in the steam workshop, Awesome !
The gameplay is quite a step up from the previous game even though the released game itself lacks content such as more weapons and aircraft, but I understand Bohemia is working on free DLC to remedy that..Also mods from the fans also remdey this !
Arma is not Arma without the community behind it, so far it seems like it is. Can't wait for the future of Arma when it fully kicks off.