Of course a sat-nav is only as good as its mapping, routing and driving instructions and I've no complaint with the C620 here either. Calculation and recalculation is very swift, even with the longest pan-European routes, and the route choices it makes are sound. Even if you don't like what you're given, the C620's peerless map browsing and panning abilities make adding waypoints to routes an absolute breeze. If I have one criticism of the voice instructions it's that they can get a little insistent and over-repetitive at times, but this is better than having it the other way around and they are at least timely and easy to understand.
Add full European maps and speed cameras, a fantastically bright, readable screen (one that is easy to read even in very bright sunlight), a loud, clear speaker and a design that's slim and light and, in my humble opinion, you have a viable rival for TomTom's all-conquering Go series of devices.
But look closer and you'll find plenty of areas where this Mio can't rival the Go sat-navs. The latter's Map Share technology, which allows users to correct map mistakes and download others' corrections, is more useful than any innovation the C620 can offer. There's no light sensor or microphone in the C620 either to adjust screen brightness and speaker volume depending on environmental conditions, no FM transmitter, no speech recognition or text-to-speech engine. The Mio still can't quite match TomTom on PC integration either, and its optional TMC traffic upgrade isn't as powerful as the equivalent TomTom service over GPRS. But despite all this, I think that TomTom's Go 720 finally has a worthy rival.
Mio's C620 is a fine sat-nav and it's not because of the gimmicky 3D landscape and landmark features, though they are nice to have. It's because it has finally combined its undeniably good mapping engine with an interface that is now practical, polished and elegant. The Mio C620 might not quite compare with the TomTom Go 720 on truly useful innovations or sheer feature count, but it is clearly the best of the rest, and at £246 including full European maps and speed cameras, works out pretty good value too.