I could never really get the hang of them and that sort of twitch gaming isn't my thing. I bought Crysis 2 and tried it for a bit before I just gave in and gave it to my brother. And if I can't invert both axes, then forget even trying - I just can't cope with the camera going right when I push left, or up when I push forward... They seem plenty popular though, CoD breaks sales records with each (unnecessary?) yearly installment...

But! I played one game from a first person perspective last year and absolutely loved it (and bought the DLC)! A bit slower paced than most shooters and with a definitely stronger narrative thread, I urge anyone who likes shooters to give Deus Ex: Human Revolution a try. Yes, it was published by Square Enix and I already admitted my brand loyalty there but the developer was Eidos Montreal, so I'm not just being biased :)

http://www.deusex.com/