Multiplayer is fast paced with team deathmatch and combat mission modes being the most played, there's also a domination type mode where you have to capture points on the map and a defend objective mode - maps are small and narrow to keep the action focused, just don't bother getting the paid "hotzone" dlc pack for the game
nobody bought it.
Not a massive community playing but it's not completely dead, check here for server population.
http://www.gametracker.com/search/moh/3000/?sort=c_numplayers&order=DESC
Single player campaign is a short 4 to 5 hour affair, they split up the teams when making the game, DICE did the multiplayer portion on the Frostbyte engine (think Bad Company 2 but without the over the top destruction) and EA's Danger Close did the single player using the Unreal Engine.
One thing that might turn people off is that EA made some weapons truly exclusive for a pre-order perk, the only way to get them is to have purchased the game from specific places such as EA's webstore or Gamestop. I don't believe that you get access to these weapons from D2D.
M240 & RPK Light Machine Guns and the MP7 were EA webstore exclusive
M60 Light Machine Gun was the Gamestop exclusvie
There's no way to unlock these weapons from normal progression through ranking up in game.