I chose the Mecablitz over the camera manufacturer's proprietary flash as it was significantly cheaper. It is more than adequate for my needs. Construction is of fairly dense plastic: there is a screw to lock it into the camera's hot shoe and the flash head rotates and moves vertically with positive click stops. In the bounce flash position the head will not support much weight, so forget about using a large diffuser. There is a small, flimsy, built in white plastic reflector that is fiddly to pull out of the flash head. It is, however, better than nothing. The zoom range is 24-105mm, which can be extended to 18mm with the built in diffuser. This pulls out along with the reflector: indeed, the only way I can get the reflector out is to pull out the diffuser and then push it back again.
The flash unit is fairly large: almost as big as a small DSLR, though not of course as heavy. It takes 4 AA batteries. I use rechargeable NiMH batteries, and if you do not already have any, it makes sense to purchase rechargeable batteries and a charger. Fully charged, the flash batteries last as least as long as the camera battery, which is just as well as there is no indication of how much charge is remaining.
The Mecablitz's LCD display is easy to read and can be illuminated if necessary. The four buttons at the back of the unit control everything - if you can remember what they all do. Exposure compensation and mode change are simple enough; anything else may require a look at the manual, which describes all the functions clearly enough but assumes some familiarity with the technicalities of flash photography.
One technicality with which I was not familiar was the rating system; 48 feet sounds impressive, but this is at f1.0 (I don't have a lens that fast) and at the long end of the zoom. The actual reach at ISO 100 is the guide number divided by the f number. The flash calculates this and displays it on the LCD panel. In practice, however, I use ISOs above 100, so 48 feet is obtainable. It is quite possible to photograph the interior of a small country church with this flash as the main illumination.
I use the flash mainly for macros. To this end the head depresses by about 5 degrees; not really enough to point directly at anything within a foot of the lens. This is not a problem though as the Metz is so powerful: putting in the diffuser to increase its angle of coverage helps; it is still often necessary to turn down the power manually to avoid harsh lighting.
In common with almost every other piece of photographic equipment I have used other than my Panasonic L1, the Metz sometimes declines to function. Removing and replacing the (same) batteries wakes it up again.