Recommended for anyone.
Basically, this game takes Rome and improves everything. If you are a veteran of Rome, then you can just sit down and start playing this game without any tutorials or manuals to go through, and no patches- which is a great thing in and of itself. Rome had... what? Four patches? This game is good to go right from the start. Everyone say a collective 'Yay.'
In terms of the real time battles, little is changed, though I imagine you've heard of the improvements in the graphics department.
One thing really sticks out to me, though. It kind of bothered me how in Rome units would swing swords in the air and never really contacted the enemy. Just swing in your foe's general direction and they die. Not so in Medieval 2. Swords hit swords, shields block blows, and it's not uncommon to see one of your men skewer another soldier foolish enough to engage him. Battles are basically butt loads of sweet duels between individuals, Braveheart style. Good stuff.
All in all, this game is well worth your money and time. Don't forget to get some fresh air though. And a good night's sleep.