I visited the official van Gogh museum in Amsterdam after visiting the big brother (Rijksmuseum) before. Seeing multiple museums simply is too much for me.
So; what did I think of it? I think it's much worth a visit. Of course van Gogh is a little bit cooler to me since I'm also Dutch, but his art is really great to look at... coming from someone who's not all that crazy about it.
But there's some art which really needs to be seen first-hand. Photos or posters or replica's don't do them justice. Seeing them how they were meant to be seen with good lighting is a whole different story! I saw that with some paintings from Monet which were displayed and some van Gogh's, the difference is appaling.
One of these paintings is By The Sea by Monet:
This painting is hauntingly beautiful seeing it in person, an image is very pretty but doesn't come close to the real thing.
And another one of those is the Sunflowers in 3 shades of yellow by van Gogh:
If you're in Amsterdam and have the time to visit both Rijksmuseum and Van Gogh; go see them; they're among the best collections of art in the world!