I mean as far as unlocking every single attachment for every single gun.

It is pretty damn challenging, but it helps to make you more well rounded.

At the moment I have completed every single assault rifle, all the support weapons with the exception of the MG36(about 50 more kills), LSAT, and Type 88 LMG. Still got quite a few of the Carbines for engineer, and have only scratched the surface with the recon kit, I think I have only finished M40A5 and SV98.

The only weapons I never really plan to finish is the shotguns, you have to get 400 kills with those damn things to get all the unlocks, but I am sure at some point I will get bored, decide to put myself through more misery and attempt to ruin my k/d via shotgun.