Hi Chris,
Franck Muller has long been viewed with some cynicism and/or skepticism by watch enthusiasts, partially for their use of relatively standard ETA movements in very expensive watches, partially because of the hyperbole of the marketing claims (Master of Complications) and perhaps in part due to the distasteful public mud-slinging between Muller and Sirmakes a few years back.
I think though that brand has made some real efforts to increase their horological prowess and reputation with significant in-house manufacturing capabilities, dedicated schools and apprenticeship programs and continual boundary pushing complications on the high end. For whatever reason, they still don't seem to enjoy the credit many feel they deserve, but good work does not generally go unnoticed forever, so the extent to which they are delivering it (good work) will hopefully become more apparent to us watch geeks over time.
_john