I'm pretty happy with this FPS. There is an issue of team balancing that is not yet fixed though people still play. Having the ability to customize your character & gear is something I really enjoy. It makes your lethality unique. Though just as with any FPS, there is plenty of camping/snipers & in some cases people taking vehicles just to destroy them on your team....
Of the two most popular FPS games right now MW3 & BF3, I would say it just comes down to preference with which you prefer. A style I guess you'd call it. I think BF3 would be more for adults were as MW3 might lean towards the younger gamers. But, it's just a guess. Based on what gameplay you're looking to be apart of. I still prefer BF3 over MW3.
The character interaction/interface/responsiveness is wonderful in my opinion.
You may become angry easily if you end up getting killed soon & often when you first play. Try not to get annoyed.