I'm often the most critical of badly thought out design and software, but I have to say that the Tom Tom 520T surpassed my expectations. There are one or two niggles, of course, but overall it's a great package.
Firstly, as another reviewer pointed out, this does not come with free traffic for life, at least not in the form of the subscription service.It does come with the RDS receiving aerial which would otherwise be a £50ish accessory for the standard 520. While I'm on the subject, it doesn't work too badly. I do find it takes a while to lock up to a station in auto mode. I haven't tried it in manual mode yet. I guess it might lock in faster that way, but if you're on a 15 minute trip to work I doubt it's going to help you much. On longer journeys I've found it' worked ok, bu some of the expected delays need taking with a pinch of salt; one example was an area of roadworks that is a bit slow flowing and it was suggesting 47 mins delay when realistically there was no more than 1-2 mins.
As a sat nav it does work very well. Address input is easy and can be done by voice (although it does require a couple of button presses to get there) I found this works very well, taking you through a process of City, street then number, providing options along the way. eg You say London and it might bring up 4 numbered options of words it thinks you said and you simply call out the number that is correct. Clever and effective. Postcode entry etc is all as you might expect.
Navigation instructions are available in two flavours; computer generated and spoken. The spoken ones are samples of real voices, there are a few that come with the system, and more that you can download/buy eg John Cleese etc. Additionally you can even record your own. I think there are about 40-50 phrases that you have to go through. However, I really like the computer generated voices becase I find the instrcutions are clearer, especially in towns. THe main reason for this is that it will give you road names a well as numbers, whereas the spoken version will only give you road numbers (plus the turning instructions obviously)
THere is an abundance of Points of interest, and you can select which varieties of these are shown on the maps. I have found some of the fuel station locations to be a little inacurate - either missing on the map but there in reality or worse - there on the map but missing in reality. But that brings me round to one of the innovative features of the 520, the map corrections. This allows you to correct, and add certain information to the maps. Better still, you can share your corrections with others and download their corrections too. There is a choice of updating your maps with only verified corrections, corrections made by many, or corrections made by few.
Speed cameras seem to be well notified, but there is no distinction as to which direction they are in. So you will get warned about cameras even if they are on the opposite carriageway. In defense many of the single carriageway cameras can cover both directions, so better safe than sorry.
Additionally the 520 tells you the current spped limit, in the bottom right corner, and your current speed. It will also warn you if you go over the speed limit by more than a few miles an hour. (You can turn this feature off) It is quite useful though especially in built up areas where the speed limits often change a lot.
There is a function for you to tell it what time you wish to arrive, and although perhaps a little conservative, it will estimate that pretty well. Estimated time of arrival, minutes ahead or behind, miles to go and time to go are all shown. I found this to be quite relaxing really as I didn't feel the need to rush (esp as I knew I didn't have to worry about finding my destination)
Next great feature is the bluetooth connection. This linked to my phone with ease, and verbally confirms reconnection each time you start it up. This connection allows you to upload your phone addressbook to the 520, make calls, receive calls, make and recieve texts - it will even read your texts out to you with the computer generated voice (sometimes with hilarious results, but it shows you on the screen too, so all in all it's good)
There is an ipod cable available which will allow control ad audio connection of your ipod (I believe) however - I don't have an ipod and the 'audio cable assessory' is ipod only, the additional cable is for audio out, not in. Furthermore the ipod cable plugs into the same socket on the 520 as the RDS traffic aerial, so I suspect that there is no way to use them at the same time.
Phone and voice recognition does lose it once you get up to speed, so I am thinking of getting the microphone accessory, but I am wondering if that also might use the aerial/ipod connection. THere is some space for internal storage of photos, music, audiobooks etc, but this isn't very extensive, and in my opinion you would be better to invest in some SD cards for that kind of thing, esp as 2Gb cards are pretty cheap now, and that's quite a bit of music. There is a built in FM transmitter to connect to your car stereo, with 2 memories to store frequencies. THis will give instructions, phone, and music over your stereo.
Power in is via the mini USB post in the bottom and the unit can be charged in the desktop USB cradle designed to sit by your PC, or using the 12V adaptor for in car charging. Alleged battery life is 5 hours, which should be more than enough for pedestrian activities. THe screen mount sucker is good and the unit slips on and off easily, but is held securely once it's in. I also got the standard carrry case, and once you get the fact that the unit only goes in one way round and one way up it's tight, but fits well and feels protected.
SUMMARY: Overal a very well featured machine. Quality traffic info will still cost you a subscription and the fact the you can't use all the accessories at the same time is a little annoying. However, I think this still offers great value for money (esp at the Amazon price) and I do believe will make my driving less stressed and safer.
(For those that are wondering, as far as I can tell, the 720 appears just to have more internal storage (on hard drive rather than ram) and full european mapping included.)