I recently ordered a 2017 M6E, but during the build time, got a 2018. They're slightly more expensive apparently, but had paid up front, so cost me the same. Also, didn't come with the standard tyres, but Marathons instead, which saved me a job and a few quid (although I might switch them to Kojacks like my 2016 M2L as haven't had a puncture since buying a CO2 inflator).
As well as the new brakes, the pedals look improved (although, I switched them straight off for SPDs). Also, I'm not sure if this was introduced on the 2017 model already, but the grips are no longer glued on, and can be quickly and easily removed by undoing them, in my case, for some Ergon GP3s. Seat-rails also are black now. I'm not keen on the bell mind you. It's conveniently located, but makes a pathetic 'ting' that would barely scare the birds away if used as a cat bell.
Not sure if this is just my one, or that my slightly bent M2L was just getting bad, but the frame hinge on this new one seems to be the easiest I've used.
The new brake fittings also mean that pre-2018 front mudguards do not fit (although you can ream the hole a bit with kitchen scissors to make them fit)