If I had to guess ...

... I'd guess that most previous negative reviewers use the transmitter directly to the actuators, while the most positive reviewers put it to the CCU / CCU2. The thing is that is the prime example par excellence of how inefficient and expensive it is to use HomeMatic components without a central, rather than from the outset to use a simpler system that is designed for server-free operation:
- In the direct pairing can be feed to the transmitter only two devices with unique switching states; not even toggle commands are possible.
- During operation of the CCU, however, you can send eight different commands that can be assigned as desired and differentiated via system variables further (so that, for example in summer operating other devices / values ​​are switched as in winter mode, by day, unlike at night etc.). In addition, here you have the comfort that the sender does not have to directly control the actuators, but only programs within the center. So you can change the programs to be executed namely at any time on the headquarters, without having to transfer new data to the transmitter - even remotely via VPN when there is no possibility of contact between headquarters and stations.

As for the hardware implementation, I have little to complain about. Especially compared to the old model with the too easy to accidentally be pressed membrane keys (your pocket you can forget because, even in a jacket pocket, it is problematic) and not very friendly for everyday lithium coin cell cuts the new to lengths better.
The size of the transmitter is likely an optimal compromise between pocket suitability and the use of a "decent" battery (ie no button cell) represent. The unprofitable Monster Keyring is best done from the same, then the thing fits without corners, edges and pain in the pocket. (!) Pressure point and resistance of the flush buttons I would be optimal call: Just hard enough to avoid being accidentally fail operated by coins in your pocket, and clearly enough to clearly differentiate a long press of a short. The Vorrezensent that there will be more comfortable with a DIY remote control will have its probably never put in the bag, but lie on the living room - now, for this purpose there is in the HomeMatic system other stations with tailored properties.
Less useful is the virtually symmetrical shape (in the dark you have to first time sensing to the middle keys, the dot marks to dodge not in vain on the back). As for the shape of the top and bottom button, the product designer has obviously had anything in the design in my head as the thumb of an adult Central Europeans, who has to grind out with that thing.
If the housing has a straight and curved sides and four almost equally sized keys, it would be worth my five stars. So just four.