I'm fairly anal, nothing I buy that costs more then $100 is bought without serious research, with the case of firearms, nothing that has less then 6 months worth of research gets bought... Regret is an expensive word!!
That said, I tore down my Ruger 22/45 and couldn't put it back together... busted out the exploded diagram, and took me about 2 days, but I can tell you, I learned so much about the gun.. Now I'm fairly comfortable with it.
Bolt actions like mausers are fairly easy; guns like Glocks are fairly easy and straight forward as well, I've not owned a 1911 and so I can't speak about them..
But guns are durable because most are simple; not as complex as say a computer by a few factors.. When I teach a newbie, I breakdown the gun, so they know where the bullet goes, etc.. and how a gun works... Most have told me they are more comfortable with the gun after the explaination.