I absolutely adore Sandstorm. And this is going to be my number one FPS for a long while to come. I like it almost as much as ARMA III, if anything it's a darned close second.
However, I have some gripes about that progression system. It's killing me, man. Haha. I just don't like how slow items are to come by after level 10. Maybe it's just me but I think it has to change. Maybe increase the amount of credits earned as you rank up? I just don't think it's fair to work so hard to level 20 and get 100 Credits at the end of the line. I imagine it'll only get worse as I level up.
Also, leveling up from local play, that is a must-have. Sometimes I just want to play offline, and it sucks that I can't get any points for it.
That said, did I mention that I love this game? because I do!