I guess it depends on the doctor. Before the surgery, my urologist warned me that I would probably be impotent -- he was right! But he has since also conceded that that even though I haven't had the nerve sparing procedure, there is a slim chance that I might regain some natural function. To my thinking, it is better than no chance at all. Isn't it funny how a slim chance and a fat chance are the same thing? 
Many people here have the nerve-sparing procedure, and the outcomes then are much better. Some have even reported getting erections while the catheter was still in! But often the nerves are damaged and take many months to recover. So we're all different.
And it greatly helps if you don't have ED before surgery!
As far as treatments are concerned, yes there are. For severe cases like mine, direct penile injections work (Bimix, Trimix, Caverject). The vacuum pump (VED) also works, although I have yet to master the use of the constriction ring. Finally there is the penile implant, a last resort as far as I am concerned, but apparently very effective.
For less serious cases, there are pills such as Viagra.