I ordered the Visira PDF at RPGnow.com for $10, which is about 130 pages detailing a single city. I have read half of it and so far it seems well worth the money. It is a fairly interesting and unique city with an evil bent but I think making it unique and interesting comes at the expense of generic and easily insertable (despite the designers claim otherwise - neighboring geographic features play significantly into its current shape and outlook). If you want a fairly (but not completely) detailed city from scratch and have no preconceptions of how you want it then you could use as is. If you want a city that meets certain expectations you will have to modify Visira, and possibly quite substatially, depending how far your vision differs from the designers.

I personally had a pretty detailed preconception of the city I wanted and will have to modify Visira in a number of ways. Not that their design is bad in anyway, it is just different. However, many things I have seen so far I liked so much that I am modifying my city to be more like Visira.