Seeing this episode a bit later than most, as I am traveling overseas, I had time to review a few ideas (and spoilers) before I entered the lab.
The episode is great because the raison detettre of the series still resonates but... the "sitcom factor" is destroying the uniqueness that actually was the genesis of the programs success.
Sidelining the funky-science quirkyness of the core group and their interaction with "world-wise" Penny - or even the individual nuances of the guys (e.g. Sheldons "D&D" throw-backs("mortal enemy" and many other things)- or Raj having oral problems with girls (pun intented) - or Leonards constant attempts at normalicy... ;-) in favour of plebian bf/gf matters (Howard and Bernadette) is "dumbing down" the series.
A great idea was under utilised - as were the abilities and dynamics of the STNG actors with the cast.
As noted - the core is still there and the writers can still produce but the material seems to edge toward mediocre themes at times - divergent to thedilithium plated thematic of yore.