In the right company, it's legitimately one of the finest and most psychologically pulsating multiplayer games of this generation. Sadly, you are unlikely to find the right company on Xbox Live or PSN. An endless succession of jump-happy, roof-running game-ruining idiots suggests there is still a lot of resistance amongst mainstream gamers to play online at anything less than full pelt.
This. On paper the whole idea of AC MP is just amazing, and I'm sure when UBI came up with it they got really excited and thought they were on to a winner. However nowadays, as mentioned above, certain gamers live life at full pelt and cannot be patient. So the MP hasn't lived up to it's full potential, which is a shame.
Now I remember Splinter Cell: Double Agent (also by UBI) about 5-6 years back which was about stealth and most of the time games were thrilling. There is many possible reasons behind why that was but the 2 major points I would say are because of how gamers have changed but also the way the game was set out. Basically 1 team was the underdogs and stealth was the only way to succeed while the opposition had weapons and, on paper, had the upper hand. Now AC doesn't have such differences which is why IMO AC's MP lacks. Gamemode dependent, all players are on an even playing field and while playing stealthy has its advantages there is no reason not to run about, other than reduced kill bonuses. I'm not saying full auto guns is the answer and remove the ability to climb (it's AC for god sake) but, individual game modes aside, there should be more differences between teams, perks and abilities etc. However it is a big ask as games nowadays are all based on fairness and balancing, which also explains why most MP games become a bore so quickly.