Very good but not extremely precise

I had a little problem installing the clamp in first. As there was not much space around the red (phase) from the EDF to the electrical panel breaker, I initially installed the clip as I could without being able to close it completely. So was erroneous readings (40% real). After moving a little phase cable I could put the clamp properly and there the numbers are much more consistent.
By cons as it is put in a commentary in English on amazon.com for this product, the "resolution" of the device is about 16W, which makes for low consumption accuracy is not very fine ( 16w, 32w, 48w, 64w, ...). This is because the device allows measurements up to 71 amps with 1,024 "no" (71/1024 * 230v), so small consumption a few watts are not visible.
see http://www.amazon.co.uk/review/REWS9AXYR6SEG/ref=cm_cr_pr_perm?ie=UTF8&ASIN=B0041H6VXI for explanations in English.

Otherwise the device is very convenient, the wireless link between the transmitter and the receiver even walk with my transmitter enclosed in metal electrical panel. The display is easy to read and attractive although a bit thicker.
The software works well (on a Windows 7 update) and is rather well done although not necessarily intuitive.
The ability to export all data to CSV is useful (at least do it once a month to avoid losing data).
I have not yet verified the difference measurement with the electricity meter but I think it will be up to 10 to 15% as announced on the product.