Downloaded it and played a few games. Wtf do all FPS's now have to have the whole "exp" BS? Turns me off so fast. Anyway, the actual gameplay is fast paced kinda fun.
Although you do get a separate set of points during matches that can be used for base upgrades and orbital strikes, the EXP system here is not so much like consoles (cod, bf3) and more like planetside. It is also required as an alternative method to the pay model.
The game does a great job of giving everyone the basic classes, you have a light class for flag runs, a medium class for attacking, and a heavy class for defensive measures. Each of the 3 classes you get can pretty much handle all roles if need. You gain xp in matches that you can then use alternative to the IAP currency, gold coins. These can be to upgrade equipment (generally 3 levels, 2 give more ammo, one increases refire rate or adds damage), open up the new classes, and buy new weapons.
The classes are fairly well priced, after a night of gaming I had enough to unlock any one class so within a week you could have unlocked every class if you wanted. Perks (think, glyphs from WoW or implants from planetside) cost a lot to unlock but not so much to upgrade, so you will find it realistic to max out your fav ones but not realistic to unlock even most of them.
The unlocked weapons are not upgrades nore are they side grades, but rather offer a new utility for special circumstances. For instance the juggernaut has a replacement for the motor that explodes in the air and showers the target with a much wider spread of weaker projectiles. It's nice for dispersing up the flag area but useless indoors and on heavy armors. They are pretty expensive too and are really there for something to shoot for when you have nothing more you want to spend xp on.
In the end there is not a feeling of overpower between you and someone with a lot of unlocks. You can kill if you have the skill and you play a role that you can cover. Jugs are a very efficient flag/gen defense, and pathfinder is pretty much what is used to cap flags and harass the enemy. Work on up from there. Planetside was the same way, your level translated into how many points you could use to unlock the other armors and weapons.
I was a big tribes 1/2 player and while things have changed (you sort of had a choose your own load out based on the 3 armor types, so now you are more restricted by what class you choose) the game doesn't feel any worse or better because of it. I suggest that if you want to be cheap, but you plan to play alot of it, spend $10 to get the %50 permanent xp bonus and also to help unlock some of the expensive perks for your main class choice.
Since no other game has really been like tribes, this is a wonderful version of it unlike tribes 3 and is a shooter I can spend many hours on. Call of duty and battlefield simply never did it for me.