Having fished all over this country, I will throw my .02 in the ring just for discussion purposes. Montana is the last place I would travel especially with all the other options around the country, which have 1/10 of the people and much better fishing. SOme of the streams are legendary, but most of those are disappointing if you fish the tailwaters here with any proficiency.
I guess if someone has never been out west Montana is great as there is a plethora of info to make it easier to find places to go, and it is somewhat historic in terms of rivers. Scenery is nice, but the crowds suck and the fishing just isn't as good as other parts of this country.
Don't get me wrong, there is some great fishing in MT, but there is much better, less crowded places out west.