Played like 6 matches yesterday with a full team with mics. It felt fresh and new at first but by the end it was starting ii feel samey. The glitched weapon unlocking being the main reason why. It doesn't really have anything to work towards. It is fun though. One map ( highway I think ) is pretty awesome.
Does the weapon not unlock if you progress through the full bar? Because I'm seeing the Rumbler starting to unlock after I did all the rank 1 challenges for the Marksman. To me it seems like you have to do the Marksman challenge first, then the weapon progression will start unlocking.
I suspect it's one weapon unlock challenge set open per Marksman level, with the rumbler being the first unlock.
It's going to take me while to get the requirements to totally unlock the rumbler though, since I don't really play KZ all that much anymore.