I don't play a lot of multiplayer games, so I can't give any good comparisons or offer anything of use in that way, since I have an unconditional fear/hatred of competition, but since the game rankings don't only give you stuff for getting number one in the whole gd world but rather based on how many/how good of kills you make, I thought it was pretty fly.
The only mode open as yet is Wanted, which is basically EVERY MAN FOR HIMSELF DEATH EVERYWHERE AAAAA which is, yes, pretty much what I was screaming at some points. (With a successful kill one time, too!) The Rome and ... one other map I don't remember the name of are available, but I spent most of my time playing on the Rome map because it's hard to find people playing in the pre-beta for some reason, AND the internet at my friend's house kept dropping. Also, glitches. I think those had something to do with it. So for the most part, the Rome map, which has open buildings and running around and plenty of fun toys to use to get up to the rooftops/cut off your pursuers faster.
Not all the characters are immediately selectable. I think that, as you rank up, you get access to more; so far you can only reach the 20th level, and around then you gain access to the Smuggler along with all the others you have.
The ranking system works like this: as you play, you get points. Kills get you points, as does escaping from pursuers. Running up to someone unstealthily and shanking their ass to high heaven gets you a basic 100 or 150 points. Escaping is generally 100, I think. You can get higher points by doing more awesome kills. Not going into high-profile mode, flanking your target, aerial kills, acrobatic kills, killing while hidden, killing while THEY'RE hidden, and poaching other people's targets (if there's more than one pursuer on a target) will all get you extra points, among others I'm sure I've forgotten. You can get a whole bunch of bonuses at once to get more consecutive points. The highest I've ever seen someone get was 900. I have no idea how they did it. My highest is around 600.
So, from the points you get, you eventually level up. Through leveling up, you get access to more abilities, perks, what I think are passive abilities (to help if you really start to fail, or if you're doing really well), and more slots for all of those, along with extra profiles. The profiles are where you arrange your abilities &c for easy picking between deaths or matches. You can reselect a profile each time you die - you're not set once you choose one for a match. Does get a little annoying sometimes, though.
SO. Hiding. Running. Jumping, stalking, killing. They all basically work like they do in Creed2, with the bonus of not having any guards around to chase your ass into a corner. Killing other targets will likely get you noticed by pursuers. The number of times I was killed as I was glorying in a particularly fine stealthsmash is ... higher than I want to admit to SO. This also includes all the unhappy parts of the climbing ACreed, which means that leaping sideways is a pain and yes, you will slam straight into a lot of things, or jump where you don't want to. And your targets get away. And sadness reigns.
I know there are way more observations I could make, but I'm forgetting all of them. I'll add more later/make new entries later. But basically: when you are getting repeatedly killed in the game, you are sad. And angry. Your swearing vocabulary will get a workout as you're hurled, again and again, toward the floor in a slow-motion death strike from some jackass on the other side of the country, your body clipping through the ground or falling in the wrong direction as the camera because this is the pre-beta and graphics are a minor concern in the way of making sure everything works properly otherwise. But while you're making tons of well-stalked kills - while enemies are running around the corner right into your loving and deadly embrace of needles and various other sharp pointy objects - while a ridiculous screaming chase scene ends with you locking onto and hurling yourself bodily at the enemy in a fantabulous win of really badly spraying blood - then it's the best game in the world. You are King, sitting atop the highest towers of Rome, exulting in your rank at 1st (which I managed to get at least twice, a miracle given my multiplayer skills) as you watch people run frantically from their pursuers across the rooftops of a rather small portion of Rome.
And then three dudes will come running after you and shove you off the tower, because the higher your session score is, the more people come after your ass.
Dearest Ubisoft, fix the clipping problems and all will be well. Or at least let me fall through the world again. I can live with that.