Anyone can play Homefront online, but not everyone is going to be able to rise through the ranks.
If the idea of battling against a communist Korean empire in the not too distant future sounds appealing, then Homefront might be just the game for you. If you want to get the full online experience though, you'd better have either bought it new, or be willing to shell out for an online pass.
Online play won't be completely cut off to those who rent the game or buy it pre-owned, but it will be pretty significantly limited. Every multiplayer map will be available, but players will only be able to hit level five, whereas people who bought the game new will be able to go all the way up to level 75. Players without a pass can play for as long as they like, but they'll never be able to progress beyond that level cap. It's not clear exactly how the leveling system affects the gameplay, but it's reasonable to assume that players unlock new weapons and capabilities as they go.
Some gamers will inevitably rail against online passes in any form, but THQ's solution actually seems like a pretty decent compromise. It's not an all or nothing deal, and instead gives players the chance to check out the multiplayer mode and possibly entice people who might not have paid for it into buying a pass. It actually seems to have a lot in common with the way that free-to-play games are structured, and that might not be a bad model for online pass systems to emulate.
Homefront comes out for PC, PS3, and Xbox 360 in March.