The Museum of Sex would have absolutely garnered a 4-star rating if the admission price hadn't been so high. Circumvent that little catch by looking out for $5 off coupons in local papers and magazines or taking advantage of the student discount.
The MOS is the first museum of it's kind in the country, and it does a good job of balancing between too much smut and being too clinical. When I went the feature show was pin-up girls through the ages and the entire first floor was filled with photos from shortly after the invention of the camera to the 1960s. Sure, they were nudie pics, but they were arranged above a cultural time line and punctuated with intelligent social analysis.
The second floor displays ran the gamut from conservative vintage sex manuals for married couples to sexual devices (both to enhance and inhibit sexual response) through the ages. Again, not clinical, but not lascivious - all in good fun.
The third floor - the Stag Film Exhibit - was possibly the only place I felt vaguely uncomfortable. The entire room is filled with stag films from various eras up to the 1960s being projected in endless loops, with taped interviews with men about the whole stag film experience available along the side wall. I had no problems with the films - again, people having sex, but in a historical context - it was just weird to look up and realize that I was watching porn in a room full of strangers.
The museum is a little small - especially for $17 - and the collection seems slightly limited, but it's new and one-of-a-kind so give it time.
Oh, and don't skip the gift store on the way out - nudie playing cards for boys and girls, art books, novelties and a selection of adult toys by way of Toys in Babeland.