I've tried and tried but I just got to admit that usually the MP just isn't very good. If you happen to get to a fair match by some sort of weird luck, it's actually pretty good and balanced. But majority of the matches aren't. At all.
Outside of DM, the weapons are pretty balanced, but the perks aren't. You really don't get good abilities until like level 22 and you have to buy upgrades for them anyway. If you have been careless, you are shit out of luck. Buying the abilities doesn't bring any more stategy to the situation than let's say the system in Call Of Duty. What's the point of unlocking weapons by levels if you have to spend skillpoints to actually use them? If everything was available from beginning, it wouldn't be such a problem, or everything was available from certain levels it would be fine too. The middle road is just useless, if I recall right Uncharted does this too but the money there is way easier to accumulate than the skill points in R3.
Further more and by far the biggest fault is the goddamn crappy matchmaking system. If I remember right it was supposed to be improved in 1.04 but was it really? Most objective matches end in SECONDS because the other team just dominates and for the second round it's ten minutes of spawnkilling. WHY THE CRAP THERE ISN'T A VOTE TO SHUFFLE TEAMS? OR BALANCE THEM IF IT'S 8vs4? It's been there almost since the goddamn beginning of online FPSs and there is no reason not to have it, especially since the matchmaking system sucks. Individual skill doesn't matter at all and it's impossible to try and teamwork when you are getting dominated to your own spawn. Tiered servers would be better but I know they aren't happening, but shuffling teams isn't too much to ask.
From the technical point of few, other than missing those very basic functions, is now pretty good as the lag is mostly gone. But has Insomniac even tested the local 2P online? Obviously the lag is still there, no biggie, but the HUD is abysmal. For instance, pressing select covers the WHOLE SCREEN in stats, not just your side. When you die, the "PROTIP: When you are getting shot run for cover"-type of messages cover HALF of the damn screen. Why?? At least lower the opacity by 70% so you can actually see who killed you with what. Also, I am pretty sure that in DM you only see one of the scores (instead of scores for both players). And the awards cover 20% of the screen, so they could be scaled by at least 50%. It literally covers what you are aiming for. The local 2P online is really really fun but it could use some improvements (in coop, but especially in competive).
It's a long rant and like I said the MP can be really fun every now and then when the teams are even but it could use many improvements still and most of them aren't even that hard to implement (I'd assume). It's an unfair comparison, but I was playing Quake 3 in school LAN today and it was pretty much better in every aspect as far as basic functions go and the games aren't even that much different if you scale down the movent in Q3.