Someone had asked earlier if Patan was worth a visit..
Definitely, it is. In fact many these days opt to stay in the Patan area at the excellent hotels and Inns, and do the reverse (i.e. visit Kathmandu and Bhaktapur) from here. The Patan area is much better in terms of environment and space. This makes for a less crowded experience for visitors. It is only a 5 minute car ride across the Bagmati bridge to Kathmandu in any case.
The Patan Durbar square is a living museum and is extremely well maintained, and can be covered in a couple of hours. The alley ways around the square have numerous interesting shops.Edited: 9:30 pm, September 17, 2013