It was an overhyped massive disappointment. The novelty quickly wore off and they were sold to a Chinese company.
Although I had the chance to use one back in 2008, it was a novelty at best. Not a city transport as they wanted, not a small terrain crawler as the TT version they sold.
It's best use was really for shopping centre security patrols and police patrols in city centres
- PSP in Lisbon use them in the tourist part of the city, close to the river and Shenzhen Police also on the Huaqiangbei district, on the electronics supermarkets avenue - or for big warehouses or company headquarters where you have a big area with tons of warehouses and labs and want a fast way to go from point A to B.
But the price of it was the biggest no-no, specially with other transportation methods as the typical bicycle or even by foot.
Basically a solution looking for a problem.