DICE has said previously the progression system in Battlefield 3 would be improved over Bad Company 2, which offered little incentive about halfway through the rankings. They weren't lying: turns out there will be 10 times the amount of unlocks and rewards over that game, meaning you'll probably be busy for years to come.
You can expect ribbons for accomplishments like capturing a certain amount of bases in a single round, keeping vehicles in top shape, reviving a lot, and more. Medals are handed out for long-term accomplishments like playing for so many hours, while service stars are given for doing well with a weapon.
Rather than being given a different coloured star depending on your progression level with that weapon, you'll simply be given a new star each time, so enemies you've taken down will have a better idea of how proficient you are with said weapon. Up to 100 stars can be attained for any weapon; DICE says this nabbing all these will be no small task.
Weapon attachments this time are unlocked per gun rather than per class; vehicles get similar treatment. There is quite a bit of customization as expected, whether you want to go pure assault or assault medic, short or long range, or with jets, for example, you can opt for Maverick ATG missiles for anti-tank purposes, or with AA missiles to take out other jets.
For those worried rewards will overshadow actual teamwork and gameplay, fear not. DICE says, "Winning a round for the team should always be the priority, so we are making sure that even when players are chasing their personal achievements, they are contributing to the overall battle." If it all pans out like we expect, Battlefield 3 should make an addictive experience even more addictive.