I ordered the X10 for my daughter yesterday and it arrived today. It seems OK - not as large as I thought it would be. Personally, I would have gone for the Desire but you just can't tell them can you? She likes it.
My main 'worry' is if the Desire is anything like my other daughters HTC, it would at least have a glass screen rather than the X10s plastic one.
Also, oddly annoying is the lack of pinch / pull for zooming in and out on the X10 but having read up - it's apparently 'a feature' i.e. it doesn't work now and never will due to HW limitations.
Also a bit gutted at the non-budging of the £30 pm tariff on Virgins behalf considering we have the VIP pack and also another 2 mobiles with them