"Smoke grenades won't be the difference between life and death, since you can rapidly regenerate health. Yep, as long as you duck behind something for a few seconds, after taking a bullet or three in the face, you'll be just fine. You won't be able to sit on grenades or dive into a nest of angry Germans, but you'll be able to stick and move like Arnold Schwarzenegger. Even an MG42 is manageable, as long as you have something solid in between it and you. Hide, pop up, fix, fire, drop back down, repeat ad infinitum. This Wolverine-like feature will be essential in certain high-powered engagements, but I would sooner have health packs or a medic, rather than be able to take hordes of enemies almost single-handedly. It's cool for a while, but then things get a little too easy, once you get the rhythm down. And it's there on all difficulty levels, and in multiplayer. The only way you're going to die is if you can't somehow escape from a grenade or if you stumble into several enemies at once, where their melee attacks will make quick work of you. The amount of damage you can handle dwindles quite a lot as you ramp up the difficulty levels, but you'll always be able to fully recover from pretty serious damage."
http://ca.ign.com/articles/2005/10/25/call-of-duty-2-4?page=3