I think they are a lot like the UAW in that they have done some good, and some bad.
I like to call them "Negotiate Rights Away", because they have a long history of bending in on issues, especially NFA related. In my opinion, the NRA should be stopping at nothing to end the NFA, instead they allowed it to be instated, then sat idly by when the 86 FOPA outlawed new machine guns.
They have definitely done a lot to promote small arms ownership, like taking on various cities when they do gun bans and things. But I think they have more than lost their way.