The Augments trilogy begun in "Borderland" continues, and while the whole story is pretty interesting for fans of the franchise (because we revisit the genetic supermen that gave us Khan) and the series (because this whole arc kicks off the way the whole fourth season plays out), the real treat is that "Cold Station 12" finally allows us to meet Phlox's pen pal, Dr. Lucas.
Famously introduced in "Dear Doctor," Lucas is a key part of Enterprise lore. While the whole Augments arc is a tad extraneous to the series (except when revisited several arcs later), it's a little more disheartening that when we finally meet Lucas, it's basically the same thing. That's one of the hidden weaknesses of the season, which even fans who didn't particularly care for the series tended to like because of all the franchise stories, that it tended to disconnect from the rest of what Enterprise had done.
Being a fan of Phlox, I was always on the prowl for more material featuring the good Denobulan, and this was about as close to good Phlox material that the season featured. It's worth a look.
franchise * series * essential * character
Memory Alpha summary.