A few months ago my organization made the decision to make docking stations a standard item to be ordered with all Macs. We've evaluated the Belkin Thunderbolt dock, the Matrox DS1, the Kwikdock, the LandingZone docks and had previously used Henge docks.
The Henge docks proved to be a constant pain for both users and our support team. The connections in the bottom of the dock frequently came loose, meaning the end user would lose USB connectivity, network connectivity, etc even though from their perspective the Mac appeared to be docked correctly.
The Kwikdock didn't have the build quality we desired.
The Belkin Thunderbolt dock and Matrox DS1 dock are both very similar in that they're a hub that you connect all of your connections to, then connect to your Mac via a thunderbolt cable. The downsides we found to these two were cost the necessity to order a thunderbolt cable in addition to the dock. Our end users are also much more accustomed to the traditional docks offered by Dell and other PC manufacturers, were you click it into place and go. This is the same reason we didn't pre-order a Zendock.
We ended up going with the LandingZone. It offers the traditional docking style that our users are accustomed to, the build quality seems to be very good, it's much cheaper than the alternatives and can be further reduced in cost by ordering in bulk. It DOES require a separate driver for network connectivity but it's very lightweight and they seem to be committed to providing updates in a timely fashion.
I've deployed about 25 of the LandingZones so far and aside from two support calls where it hadn't been locked completely in place I've only heard good things from my end users. We have yet to receive our 13" Retina MBP docks but we do have a tracking number so I'm confident they'll arrive soon.
Hope that helps!