I've always liked this name but I wouldn't use it. The name Jan is very popular in Europe. It's like any form of John except Evan; timeless and suitable for men of any age, while Evan could only fit for young men to me...
My husband and father in law are named Jan, and are of Dutch origin. To my American ears the name sounds exotic and sexy; the sounds are all voiced with no plosives or fricatives for a very smooth, gentle, gliding sound. The name has a feeling of being intellectual and sophisticated, yet simple. In Holland the name is very common, but here it sounds unique to the point where some people we meet are hesitant to pronounce it.