Setup, and solving the adapter mess
Out of the box, I blanched at connecting a Thunderbolt 2 to gigabit ethernet adapter to a Thunderbolt 3 to Thunderbolt 2 adapter—about 8 inches of chunky adapters before the ethernet cable is plugged in! It’s not obvious how klunky this is until you see it in action—yuck.
Adding a mouse would add yet another adapter, and that’s just getting started on the dongle mess (external drive, camera card reader, and more). A sleek laptop that has to bristle with attachments just for basics: funny how the Real World is never shown in those sleek product shots.
There is a better way—while the OWC Thunderbolt 3 Dock is not yet available, the OWC Thunderbolt 2 Dock avoids a pile of adapters: plug in a Thunderbolt 3 to Thunderbolt 2 adapter, then cable that to the dock. That’s one adapter, but it adds a plethora of ports, including gigabit ethernet and Thunderbolt 2 and five USB3 ports and Firewire. Nice and 'clean' for desktop scenarios.
The not-yet-shipping Thunderbolt 3 Dock will plug in directly without adapters, but note that the port on the Thunderbolt 2 Dock is Thunderbolt 2, so any Thunderbolt 2 peripheral can be plugged in directly (and more daisy-chained off that device). Whereas the Thunderbolt 3 Dock has a Thunderbolt 3 port, which requires an adapter if one wishes to plug in a TB2 device. Either way, the Thunderbolt 3 to Thunderbolt 2 adapter is needed so you might as well get one.
These solutions are of course for desktop use, since they need wall power.
The about $149 OWC USB-C Dock works on the 13" model (tested and verified according to OWC), but the 15" model apparently has some issues when restarting the computer or powering on:
We are rescinding 15” compatibility for now… is a firmware update most likely—we are seeing some inconsistency in initial dock power up at connection on just the 15” models. Zero issue on the 13” models. But the 15” sometimes is requiring multiple plug in attempts before the dock comes online recognized by the 15” models we have.