Let me throw my 2 cents in, I had kept notes from when I first got it 2 years ago and here's what I wrote:
Pros:
Chamber size, barrel twist rate, trigger guard, small diameter rail, forged upper and lower, ambi controls (safety, bolt hold, mag release AND charging handle), spiral barrel, light weight and what feels like a low moment of inertia i.e. it's easy to change directions with it, MOE grip, LWRC SOPMOD-like stock, included BUIS, fit and finish, nickel Teflon FCG. It's a little front heavy, shoots well. I've since added a Vltor EMod stock and while it's made things heavier, it's also improved the balance. I added the LWRC panels to it because it gets hot when you shoot it, and they're a little slippery but they work.
Cons:
1) Rail length - I have long gangly arms, the option of no bayonet lug and 2 more inches of rail would be perfect. I don't need a bayonet lug so having the rail swallow the gas block whole leaving access to the gas adjustment knob shouldn't be an issue. I'm sure for other tall civilians and probably cops too, this would be the same feeling. (I'ts now offered in the A5 variant) At the rail's current length, I had to go with a HSP Thorntail light mount to put the light far enough forward that I can thumb it on without contorting my hand. I also would like to see M-LOK slots between the threaded holes giving me more flexibility with what I want to mount and how.
2) Rail segments - a couple 2 hole rail segments in addition to the (2) 3 hole rail segments in the IC package would be nice. I want to mount a light, the 3 rail piece ends up under my hand making it feel like a quad rail gun, larger than it needs to be. I can buy one or two 2 hole segments from LWRC, so it's not a big deal, but it will add time to getting to my final setup. Also, the LWRC site doesn't indicate whether or not the SPR rail segments fit the regular IC, I assume they do (they do, bought some).
3) QD sockets - Having the QD sockets at the back is a pro. Having them only on the sides and not the middle is a con to me. I like running one off that center hole because the side ones tend to interfere with my hand/fingers. Also, having the QDs being able to turn 360 degrees, I really like. I've met about 50/50 with regards to people on this one, some like the free spin, others hate it.
4) LWRC's website is still crappy. I've ordered spare parts and luckily wrote it was for the M6-IC because I'd picked the wrong thing (piston return spring spares)
I've not tried Gen3 PMAGs in there yet, so I can't comment on how they do. I've not shot for accuracy, but I'm positive it's more accurate than I am.