Risk 2210 AD starts with the premise and mechanics of regular Risk - take over the world by rolling dice (attacker gets a max of 3 dice, defender gets 2, but defender wins ties), and then throws in everything including the kitchen sink. 2210 adds commanders, space stations, water territories, lunar territories, and special ability cards. The game is played for 5 rounds, and at the beginning of each round all of the players bid "Energy Points" to determine who gets to pick their turn order first (as in, if I bid the most, I can choose to go first, or I can choose to go last and try to go first next turn for back-to-back turns). After the turn order is set, each player takes their turn. First, as in normal Risk, they collect reinforcements, but in addition to reinforcements, the active player gets to collect an equal number of Energy Points. With these points, they can purchase commanders (that allow them to enter water or space, to play different cards, and that roll 8-sided dice instead of the normal 6-sided ones). Points are also used for buying and playing the cards, buying space stations, and for bidding on turn order. Once the active player has placed their reinforcements and spent their Energy Points, they take their turn by attempting to take over more territories with the hope that they will be able to collect for continent bonuses on the next turn.
One of the major pro's for Risk 2210 is that the game is very fast paced (not to be confused with short - the game will still take over an hour). It only plays 5 rounds, but this is often enough to determine a very distinct winner without even needing to count end of game totals. There are many more territories and continents available, so the chances of getting bonuses and large numbers of reinforcements are much higher, and factor in that certain cards can give you even more armies, and this means that players will have more "useful" (bloody) turns.
Another pro is the addition of the commanders and cards, as these add a new element of strategy (and luck) to the game. Now, instead of the strategy simply being to get a swarm of armies and attempt to march through your opponent, you must also decide where the best positions are for your commanders, how many cards to buy and of what type, and even whether or not you should go to the moon (after all, it's not all that easy to get back from there).
The cons of Risk 2210 are more minor. First, people that really enjoy the original Risk may not like that the game is only played for 5 rounds instead of until one person takes over the world (and moon). Also, there is still quite a bit of luck and randomness involved - as in the original, how well you roll dice will determine how well your armies perform, but now which cards you draw can also influence the game.
Overall, Risk 2210 gets an 9.0/10. This is one of my personal favorite games, but I also realize that it is not perfect. It is a game that I would highly recommend to anyone that is interested in war games or the original Risk.
If you like Risk variants, then you should definitely check out Risk: Legacy.