If the bullet severs the femoral artery, death would occur within… I want to say two minutes, but it could be as much as five. If the bullet blows through cleanly, and the blood loss is managed, it shouldn’t result in anything more severe than scar tissue at the entrance and exit wounds. If it damages the bone and that’s not treated, or treated incorrectly, it would permanently impair movement (barring corrective surgery).
If the bullet tears up the muscle tissue, and it doesn’t heal properly, I think that would result in permanent mobility issues, but I’m not 100% certain how that would manifest.
Again, I’m not a medical professional; my familiarity with gunshot wounds is academic. So, I could be wrong here.
EDIT: I’m going to attach this reblog to the main post because it’s actually really useful, and I did drop the ball a bit last night after tumblr ate my first draft of the entry and exit wounds answer. So, with thanks to Disasterintow.
Gunshot wounds vary depending on the type of round used, special attributes to the round (hollow point, armor piercing, etc), the distance from the shooter. A normal sized male (6’ 180lb) shot at close range to the thigh with a simple 9mm round would be in a lot of pain, but risks only moderate damage to bone, and supposing the femoral isn’t stuck, the most you would to be dealing is a hopeful through-and-through. That way, as mentioned before the most to be dealt with is stopping the blood flow and stitching up entry and exit wounds (the latter of which will be significantly larger).
Do. Not. Dig. A. Fragmented. Bullet. Out. Unless you are a skilled surgeon, though even these days, a majority of those professionals choose to leave non-life threatening shards inside. Removing the bullet damages muscle tissue, connective tissue, and tears nerves, all of which are needed to counteract the trauma of the initial wound. And you run the risk of more blood loss.
Now, when it comes to larger caliber bullets and shotgun shells, there is a problem with distance. Up close and personal, a .45 caliber handgun round could shatter bone and leave an exit wound the size of a Granny Smith apple. broken bones (shattered ones, at that) have a very high risk of sepsis, and if not dealt with quickly, could spread to the rest of the body.
AP rounds – Armor Piercing – go straight through flesh and have very little sign of slowing. There is risk to bones, however, as the amount of power (force) they carry with them hits full on if it meets a hard structure. The kinetic energy alone can fracture shoulder blades.
As for buck shot and slug for shotguns, those are trickier. They do need to be a certain distance to be effective, but make no mistake: these rounds will break bones and most certainly leave holes in you. Buckshot is pelleted, but deadly in a closer range.
A safe bet would be to say the person was shot by a .40 caliber or lower handgun, or anything around or lower than a .308 rifle round, and that the meat of the thigh took the bullet. If at a decently close range, that person should survive and most likely walk with a little hitch for most of their lives. Nothing too noticeable, however. There would certainly be scarring, and if nothing happened to bone, and no nerves were injured, there should be no loss in range of motion or use.