Ah, the strawberry jam to the face approach...how lovely immersion breaking and generally annoying. Sorry, but that crap just blurs your vision, making it harder to survive. Plus having generating health means that the character can magically grows his legs back after stepping on a mine. Bloody hell, it's now wonder why today's shooters are shit, and why the players of said shooters are all (without a single exception) retards.
So what I propose: a health bar divided into perhaps 5 sub-bars. Each sub-bar brings with it different penalties, eg more wobbly aiming, loud breathing, limping, inability to jump, inability to use 2-handed weapons, etc. Every time you take damage, your health drops accordingly, but will regenerate over time (we're talking minutes here, not seconds) to fill the current sub-bar. That way, injuries that are in fact serious will feel serious. Additionally, I'd like a red circle to flash up on the screen, which will indicate the direction of the shot. At least that way you'll know which hidden sniper just shot you.