With everything added together one thing is clear - this is a highly effective and very usable sat-nav. Maps are extremely clear and easy to read, especially the onscreen next turn indications. These are displayed as icons in the top left corner of the screen and with a 3D arrow overlaid on the map itself, both of which make it abundantly clear which way you need to go. I found complex roundabouts particularly easy to navigate with the S50 3D - an area that many sat-navs fall down on. The big 4.3in, 480 x 272 screen, too, allows loads of detail to be squeezed onto the screen, and you can see a long way down the road and around you, even in 3D view.
In testing, I found voice instructions were delivered in a timely fashion and very clearly and there were very few problems with the routes it chose, though it won't - as the high end TomTom's do - take into account real world journey times, just speed limits. Routes were recalculated swiftly when I strayed off route and you get 12 months worth of speed camera updates too.
It isn't quite perfect. There's no lane assistance feature as there is with the latest TomTom and Navigon devices and traffic information is not included as standard. The screen updates with a slow and stuttering action, which isn't ideal when you've got lots of turnings linked tightly together and a strange choice of which mapping details it displays makes browsing the map to add waypoints rather more difficult than it should be. Cities and towns aren't marked especially clearly in overview 2D mode, for instance, which makes finding points on the map by hand tricky.
Despite some niggles, however, the S50 3D is a usable and effective navigation device and one that's particularly good value for money. It's unique - as far as I can tell - among sat-nav's this cheap (£111) to feature a 4.3in screen and its business directory search is another feature that sets it apart from other low-cost navigation devices. More importantly, it beats the disappointing TomTom One V4 and just edges in front of the Navigon 2100 as the best budget sat-nav around.