For certain purposes perfectly usable

I bought the device to have a "Always-In-device" that you can actually always take. And as it is small and light enough. In my "case" it comes to distinguish a (dangerous?) Paroxysmal tachycardia of a possible atrial fibrillation. For this the device will suffice. Since these tachycardia (frequency to 200 pendulum) Insert completely irregular, then stop 20 to 40 minutes, and since this has happened only five times in three years, I can u. U. waiting long. The alternative to the device would be to stay always in or near a doctor's office, which could record an ECG immediately. But this is quite unrealistic, and that's why I bought the device.

First Note to potential buyers: The device only on or off when you hold down / off more than three seconds the inputs. This is, however, also in the "Operating Instructions", but with that is such a thing!
The manual is a disaster. Sample sentences I bring not better here. That makes no sense. The device is manufactured in Beijing and I also know the differences between a visual or sign language and a language of letters. It would have been better to settle a (less bad) English manual here.
This little device is, however, self-explanatory, if you are not is a digital illiterate.
Good ECGs (see photo) is obtained only if you do the recording with three glued electrodes. (10 are included, more needs to be separately purchased) The decrease in 5 cm below the heart is still usable, while the manual measurement to assess is unusable.
Software I have not installed / tested. I've had enough of the presentation on the display.

Addendum 02 of 17 2015:
I have now but the software installed (Windows XP and Windows 7), which worked with no problems. This is a manual is embedded in English, which for the one who can speak English, a useful aid. Although here are also plentiful linguistic ERRORS, but that can get over. In terms of content, at least one ERRORS, but probably even more. But with this English-speaking guide, you can come to terms.
You should install the software because it offers some other useful applications, such. As clean printouts of 30-second ECGs on A4 with underlaid graph paper. The curve is easier to see than the display-playback on the device. Note: From the print command to the printing pass 60 to 90 seconds! So wait patiently.
I recommend that you deal with the software a bit. Then, after several attempts and many trying, even without manual cope reasonably.
The Notice of Karl-Heinz Witte is incorrect; transferring the stored ECG works smoothly and even rather quickly - at least for me. When selecting / clicking on the appropriate menu item in the software and device powered up and connected the data is retrieved, which also appears on the device display.
Overall, I think that you can not expect 160 to 180. This is not a professional tool, but quite useful.