As of September 11th, the Van Gogh Museum is already partially closed off. This is why one can no longer purchase tickets online. If one were to show up at the Museum anyway, the staff will inform you of this partial closure and charge you the same, not discounted, entry fee.
Just got back... so what.. it is worth every centime...Lots of stuff you will never see anywhere..the self portraits are masterpieces and worth the ticket. Paul Elma, WA 9/22/12
Some of the most famous paintings are on display right now at the Hermitage, which is an easy jaunt east on the tram from a block north of the Rijksmuseum.
we were there on Sep 16 but didn't notice parts were closed (however we hadn't slept yet from an overnight flight so could have just not noticed). we spent about 90 minutes but could have stayed longer but jet lag was kicking in.