A rental for sure. Finished it up last night. This gives you a more realistic idea of what Modern Warfare actually is - no jetpack powered ski-doo's, nuclear explosions every other day, or outright laughable storylines begging for Michael Bay treatment.
Pretty decent treatment of the military, feels similar to the Brothers in Arms series. When the scripting works it sells a great experience as you fight your way up and down the Afghan terrain. On the other side the scripting too often breaks the immersion. There were a couple of instances where I'd steal a kill from the npc character, but then the npc character executes the kill animation anyway. There were several instances where I was ordered to flank an enemy position, and on doing so could see enemy forces teleporting into existence and promptly get killed by my team - only to teleport into existence once more. The sniping and vehicle sections are fun to playthrough.
Playing this reminded me of why Reach was such a good entry - that you were a part of a team, not some lone covenant genocidist.
Multiplay is okay, but I find more value in Halo/COD/BC2 to not abandon them for this. Sniping feels way too easy to do in this game. Which leads to most games devolving into snipefests, even in the objective based modes.
Had some fun with it, now to drop it off in the mail for something else.