I wrote this review to address some of the problems people have listed with this system so here goes. Firstly, the USB lead supplied with it is a strange L shape but I had no problem using it at all, it fits easily first time. There is another way around this by using any other USB lead. The same goes for the car charger, just use any car USB charger with the same power output.
Secondly, the maps. It took 24 minutes to download them on my 10Mb connection and then another 40 minutes to install. Not too bad in my opinion and it only needs doing once. There have been lots of talk about the Tom Tom not having enough memory to fit the maps on, well mine shows 1.9GB available on the device with only 1.6GB used and 300Mb free for extra voices etc.
Thirdly, the lane guidance. It does work exactly as it shows on the box with a nice full screen display, but only on motorways. If you come across a normal roundabout etc then you only get the small arrows down the bottom left.
Now all that's done, all that's left to say is that I love this sat nav! It's a great improvement over my old 520, in fact I "downgraded" to a Tom Tom one because it has 4 times the internal memory, the built on windscreen mount is great (much better than any other i've had) and the speaker is far louder than ever before. I have written some less than positive reviews about Tom Tom's before but i have to say they have got this one spot on.
I'd recommended buying the Tom Tom One without any hesitation. Yes of course it has the usual sat nav problems of the odd speed limit being wrong etc but just remember - when you turn your sat nav on, don't turn your brain off!