Am playing this game since closed beta(winter 2012/2013) and must say it used to be more balanced before steam release. Overall this game is fun and for sure not a pay2win.
In fact paying players get less fights as they choose to upgrade their parts to higher tiers and become rank 7's that mostly get to fight in-game bots.
As game only has 1 server, lag is a big problem and the server side hit detection doesn't make it any better(you can be killed after taking cover as you still appear out in the open for some players).
If you are a maniac that needs to have every in-game achievement done, this game is not for you(as some achievements take longer time or real money investments)...
Getting sparks is too easy I must say, so unless you don't spend them on unlocking things you can unlock by leveling up for example, stay at low ranks and don't buy accessories, you should be just fine.
You can get stuck and drive outside the maps.
When using 2 same kind devices(two ANTI-ROBOT MINES for example) you get to use them only 6 times max.
Guild speed increasing benefit has no effect at all, no matter how upgraded it is.
Leaving queue and joining it again can leave you without weapon ammunition.
Sometimes you can't drive over destroyed robot leftovers or take bomb from one.
Extremely unfair. 1 alive players gets teamed up with 4 in-game bots and goes against 5 alive players. Full team of rank 2's often goes against full team of rank 3's (no SQUADS involved).
Matchmaking is in fact most fair at rank 1 and that's also where fights start at the quickest rate, so you can be dominant right from the gate.
Very limited in spite of illusion of huge part shop. As some weapons are OP only few sets grant optimal gameplay, however if you don't mind giving your enemies an advantage you can try all other parts.
Robots can be partialy repainted, there are few parts that can completely change color. You are also very limited to the colors you can use and unlocking other colors costs huge amounts of sparks.
LADDER (a.k.a Highest scores top list):
Starting with season 3 we have leagues, basically if you can't make it into Master league you are bad at this game or you are doing something wrong...
All other leagues are a joke 30-40 wins should be enough to enter master league, if you don't lose in the process(points increase for each kill and win and decrease for losing and dying). I hate this become Master in a day ladder system...
My ideas on improving the game:
1. Option to limit team size, I prefer smaller fights where more depends on my actions(like 2 vs 2 or even 1 vs 1), and I don't have to fight 1 against 5...
2. More painting options(at least vinyls).
3. Fixing the bugs doh.
4. More complex ladder where you have to progress from league to league without skipping.
5. Heavy weapons should add more to the the robot rank (like it was befrore steam release) or maybe basic weapon DAMAGE PER SECOND should be used when deciding robot rank.