The title says it all. I personally think it can be unbalanced at moments, and some times, downright frustating. Quickboom, G-MAL and Revenge, do i need to say more? While i'll thought that some boosters in UC2 was unbalanced (like ironfist or whatever it was called) i they have added more unbalanced boosters in UC3. Using the booster (i can't remember the name of it) that reduces the "pain wobble" AKA recoil when aimed in with, for exempel, the G-MAL, can make it a long range, no recoil, burst firing sniper. Revenge, wich dosen't relly unbalance the game, have way to many time caused me to die when it's droped from a teammate that died nearby, wich can both be blamed on it being a stupid booster and other player being to slow to move away (and it being ripped straight from COD).
The medel kickbacks, wich i don't even understand why they needed i the first place, can sometimes be a real bitch. Will it's good that you need to earn them, sometimes i question why they work like they do. By this im talking about relly just one single kickback, Quickboom. Why is there a time limit to how long it works? Why not just make it work like Cluster bomb or Mega bomb? I don't know what they where thinking.
Co-op (both adventure and arena) is not all to diffrent from UC2. In adventure i (for some reason) usually get pared with player who are way lower level then me (im level 75, no legacy) whilst in arena it's the other thing around, wich is a good thing.
With patch 1.3 or 13 or whatever they added these new pieces of clohting that give you a boost to like headshot damage or something. I like how they both give a boost and penalty to balance it out, but i don't understand why they decied to make it like P2W (pay to win) and make so you can do just that, pay to get them and not earn them. Let's just hope they don't the same thing for booster.
The ability to modify weapons isen't all to bad relly. I've heard that people think that the ROF mod is unbalanced, although i never relly had a problem with it.
Blame me for being a noob but this just my opinion.