the onley problems with a shotgun are:
1, they run out of ammo VERY quickly
2, they kick really freaking hard if you're not used to shooting one.
3, they're short range (so after a couple of yards they're nothing more than an oversized BB gun.) and they can't be used to snipe off zombies at long range. (especially if you live in a 7 story building)
4, the shots scatter and spray in many different directions. (if you're by yourself you're fine, but there is a risk of friendly fire in large groups of survivors.)
5, you constantly need to reload them which takes time away from your shooting. the one i've got is an old single shot and reloading it gets really annoying.
I myself am quite fond of the soviet spring propelled knife. they can be a melee AND a covert short range gun. iwould only resort to it in emergency cases though. like when a lone zombie breaks into your base and you only have time to reach for a small knife before it attacks you.
And if your thinking about giving up and commiting suicide, i would always carry a couple of grenades on me. just because you're screwed doesnt mean your friends are. seperate yourself from the rest of the group, jump in the dead middle of the zombies and blow them all to hell. just like in I am Legend.