I bought this a while ago and have reserved judgement until I used it a few times.
When it is initially switched on it takes approx. 3 minutes to locate my position, the maps are really good, (the 2D view is a bit rubbish, 3D is far better), you have the ability to zoom in/out and roate the view 360 degrees, I have only lost signal a couple of times in areas of dense wood or when going through a valley but the signal re-locates you very quickly.
When you add up the cost of the individual parts provided (car cradle, map disc etc..) the price of the GPS works out to be approx. £60.00 which is a bit pricey.
You can download the European maps in addition to the GB and Ireland ones provided direct from the GO! website at a cost of approx. £20.00 when I last checked, but you'll need a big memory card (2gb minimum).
Overall It is excellent considering it's only an add on for a multimedia player.
Enjoy.

Used the PSP GPS to get me to (and around) the South of France this summer. Indispensible. Got me around Paris and through tiny country lanes to get me perfectly to my destination. When I bought it I thought the voice would be too quiet but found it perfectly OK.

There were 2 drawbacks though - the screen reflects the sun horrendously so took some time to get the optimum position right so I could still see the screen - and then it was still hard going when the sun was shining brightly (admittedly not such a problem in the UK!). Having a PSP-3000 will probably fix that.

Other problem was the software crashed 3 times over a 2 week holiday, rebooting the PSP. Thankfully it didn't happen at moments when I really needed it.

Overall though it worked very well and is a tool I will use a lot more particularly on foreign holidays.

I have had the pleasure of using this great piece of kit and i was very impressed. Here are my findings:

Good points:

small, compact GPS reciever, screws into the top of your PSP, (fat or slim psp)

Maps on UMD.

All the features you'd find on other GPS systems e.g waypoints, find destinations, create journeys etc. absolutely excellent.

Bad Points:

takes about 10-20 secs to lock onto satellite and now and again will drop signal if you're in a wooded area, however it does find the signal again within 10 secs i found, so its not too much trouble

pricing. you can get the GPS alone for £30 in places, so the rest of your money is going towards the software. Whilst i do believe it's worth every penny, it's still pricey.

overall - great GPS system, you will not be disappointed.