In a word, yes.
I'm writing up a review of the Metz 15 MS-1
right now. Basically it works as advertised either as a wireless TTL metering flash if your camera has a means to control it, or as an optical slave or wired flash if it doesn't.
For example it works just fine when mounted on a lens on my EOS 7D when using the 7D's built in flash as the wireless controller. I get very good TTL metering, so exposure is automatic. With something like a 5D MkI/II/III or 60D you'd need a shoe mounted Speedlite or Speedlite controller which can act as a wireless master controller to get wireless TTL metering, just as you would with any wireless remote flash. The 7D has this built in, as does the Rebel T3i, but those are the only two EOS bodies with wireless flash control built in. Wireless E-TTL flash is great for insects where you usually don't have time to mess around getting the exposure right by trial and error!
It also works just fine when wired via a PC flash cord or used as a simple optical slave, but in that case you have to set manually set the flash power, lens aperture and ISO combination to get the right exposure.
The nice thing about the 15MS-1 is that it works with the wireless flash control signals of Canon, Nikon, Olympus, Pentax, Samsung and Sony, plus it has a USB port and the firmware can be updated if Metz need to change it to accommodate another system or if one of the major manufacturers change their protocol. The added advantage of wireless control is that the 15MS-1 can also be used as a remote fill flash for "normal" (non-macro) photographic work.
It's not cheap, but it's cheaper than either of the Canon wired macro flash systems! The Canon MR-14EX Macro Ring
runs around $520, $120 more than the Metz.
If you want a wired E -TTL system but don't want to pay Canon's prices, look at the Sigma EM-140 DG Macro Ring Flash
. It looks very similar to the Metz unit except it connects to the hotshoe via a cable and controller.
There's also a similar looking wired unit sold under the "Bower" name, the Bower Dual Intelligent Digital Speedlight
. I don't know how good it is. It's cheap, but you generally get what you pay for and the Bower name isn't associated with quality equipment.