Design
The first thing that immediately stands out, particularly if you are familiar with the GO units is the ONE's case design. Unlike the GO units which resembled miniature iMac's with a squat square shape and protruding rounded rear case, the ONE has a much slimmer design more akin to an LCD TV and it can be comfortably held in the palm of your hand. There are a number of reasons why TomTom have been able to shed weight on this unit and hence the slimmer case which we shall come to later on.

Technical
Aside from the obvious design differences, the ONE differs from the GO range in a number of key areas which are worthy of explanation.

• GPS Chipset: The ONE sports the newer and much more efficient SiRFStarIII Chipset. Not only is this receiver far more sensitive than the earlier units but it also means that the ONE will happily work in situations where GO's required external antennas, i.e. In vehicles with athermic windscreens. As an example, during testing we installed the ONE in a Renault Megane. To use the existing GO 700 we needed to purchase and fit the external antenna accessory. The ONE however worked out of the box, less wires, less expense and a solution that can be quickly removed when leaving the vehicle unattended etc.
   
• Battery: The ONE has a smaller internal battery. Whereas the GO units offer a runtime of around 5 hrs on battery power alone, the ONE's smaller cell will power it for about 2hrs before expiring. This may be an issue for those of you who prefer to run their GPS units in-car on internal battery alone but for me it was not an issue. The battery offers sufficient capacity to allow routes to be pre-planned at home, POI's installed etc and once in the car I connect it to 12v vehicle power anyway.
   
• Loudspeaker: Much was made of the GO units incredibly loud and clear speaker when it was first launched. Unlike many of the competitors then available, the GO was well able to dispense navigation voice instructions with sufficient volume and clarity to be heard in the noisiest of environments, even cabriolet's and HGV's. The ONE has a smaller speaker but whilst the quality suffers to a small degree, I find the volume still more than enough for use in an average car. In noisier locations it may lack sufficient punch and there is a detectable loss of clarity and hiss but this is only noticeable when comparing directly to the GO which set a very high standard and was partly the reason for it's bulbous shape! The ONE is still louder then much of the competition.

Software

In common with the it's elder brothers, the ONE utilizes TomTom's ubiquitous 'Navigator 5' software release which has been covered in depth previously. In summary this includes full UK 7 Digit PostCode support as well as supporting TomTom's .ov2 POI format which means that the ever increasing compilations of user POI set and our very own Safety Camera Database are fully supported.

In The Box
The only thing of note missing from the box is a mains charger. In line with the budget pricing of the ONE TomTom have seen fit to move this to the options list and supply only a 12v car charger lead. A single country map is supplied pre-loaded on an SD card together with a plastic card that contains your all important Product Code (don't lose it!).

In Use

The Power button and Power ON LED have been placed on the top of the unit . This isn't ideal as the Power ON LED is the only easy way of knowing if you the ONE is receiving power when connected to the vehicle's 12v accessory system. When the ONE is mounted in the windscreen on its cradle the Power LED is almost impossible to see. You can check battery status and confirm the unit is being charged from the status screen in the software but it would have made much more sense to position the Power LED on the front of the unit itself!