Preliminary test Polar M450: one (Good ?) GPS bike Affordable

Polar confirms its interest in cycling. After V650 GPS dedicated bike (which leaves just now after much delay), the company has just introduced another device of its kind, the M450, although smaller in size and larger public. I had the chance to do a test on the ground for about a day. Here's my grip.
It seems, we are more and more of our bike ride. Among the new riders, there are certainly some who use their device in a sportier mode. To them in particular, road bikers or ATV wishing to invest in an affordable and easy to use GPS, Polar therefore targeted a model equipped with a small screen size (a square of about 3.5 cm square). The stated aim of Polar is to provide a truly easy to use GPS.
On the field
On the field, at least for a few hours of use around the Alpe d'Huez, the GPS satellite signals detected relatively quickly. The manufacturer claims to use what's best for currently receiving GPS signals: I do not know for the moment the chip used. However, in the field, for a short period of a few minutes (a total of more than four hours out), Polar M450 has lost at least three times the GPS reception. But things quickly returned to normal. 
Despite the small screen size, one of the strengths of this GPS is the great readability of data during the race: heart rate, altitude, speed, distance, the ... The assembly is particularly clear.
Site and App
The M450 is designed to synchronize with the Polar Flow site through the USB connection to the computer or Bluetooth connection synonymous with application. It's the same app (this becomes obvious now) than other devices on the mark the watch premium sports Polar V800 (tested here on HTO).
Other issues
I will not be definitive on autonomy. Just this observation: after output more than four hours, there was still energy reserves. 
But I have a regret it is not possible to follow a track (in gpx example) transferred from a computer or of an application.
Price € 160, € 200 with Bluetooth heart rate monitor belt.
I like
the simplicity of use. 
The readability of the data. 
The price. 
The Smart Bluetooth connection. 
The integrated barometer. 
The function guide back to the starting point. 
The Polar Flow associated website.