Firstly the context. I've upgraded from a TomTom One third edition and I'm writing this after 3 months UK use and a European trip through Belgium and Holland.
Hardware: certainly a large device but sits OK in my Focus and Mini. The mounting system works very well. The case I have - with a zip on three sides - is good. The reflective screen is irritating, particularly in my Mini Cabriolet with the roof down. However the excellent atFoliX screen protector fixed this atFoliX FX-Antireflex screen-protector for TomTom GO 6000 (3 pack) - Anti-reflective screen protection!
Graphics: the weakest point as others have said. The text is generally too small and not always high enough contrast. The worst example is the total traffic delay time, small text, red on mid grey, and almost illegible. I find most of the text illegible at night (pupils wider open and reduced depth of field). Some information is missing in particular the current time (usually available elsewhere in the car but belongs with the navigation information) and total journey time. There's plenty of space on the screen to fix this - hopefully with a software update? Map graphics are OK. Lanes good. The 3Drepresentation of buildings is good enough to have been genuinely useful at a tricky junction in Antwerp. However, overall it has the appearance of many inbuilt sat navs which I always compared unfavourably with my One. Legibility should be the top priority on a device that is designed to be used while driving.
Maps: seems to use the same data as the One. Generally accurate but updates take too long, eg a number of speed limits were changed in Oxfordshire a few months ago and are still not included in the TomTom maps. At least map updates are included in the cost of the device.
Routing: I found it easy to set destinations and find POIs. Quickly reroutes if you go wrong and identifies sensible opportunities to turn round - but doesn't report speed cameras off the programmed route. Directions clear. I'm using the computer generated voice which names to road you're turning onto. Sometimes useful, the novelty may wear off...
Traffic: my main reason for upgrading and choosing this model. No ongoing subscription and data updated through the inbuilt SIM card. So far so good. Claimed to save me over 30 minutes by rerouting round Antwerp and the data appears accurate. Queues and slow traffic on my route and in the opposite lane were correctly identified.
Customer service: I had a problem with my speed camera subscription expiring after day 1. Ideally I wouldn't have had the issue to start with but my query was dealt with very efficiently with a promise to transfer the remaining subscription balance from my One.
Overall I'm pleased and would recommend the device. It's a pity about the graphics, a surprising lapse given TomTom's extensive experience in producing navigation devices.