This is another classic bit of the Next Generation first season producing what could have been a lasting standout, if the series hadn't drastically improved.
Even though a Klingon (Worf) had been standing on the bridge since the first episode, "Heart of Glory" is the first time the show heavily features this famous Star Trek species. It's also the first episode to use Klingons and allow them to be, act, and end up like Klingons (unlike the two original series appearances where a forced peace occurred at the end, and the one where their mortal enemy turned out to be Tribbles). In short, it's probably the first true franchise episode of the series, and in a roundabout way is the genesis of Deep Space Nine, the only series to rely almost exclusively on details the audience already knows (with the notable exception of the Dominion).
This is no doubt a legacy of the movies. The movies gave a lot more to the franchise than fans sometimes realize. Not only did the Klingons gain their distinctive forehead ridges (thereby giving birth to all the forehead aliens in Star Trek), but they became recurring elements with lasting consequences, including the reason Kirk got his happy demotion back to captain.
Worf's backstory is the real lasting achievement from the episode. It's still surprising that Yar didn't receive something similar at some point (perhaps it would have happened had Denise Crosby not left, perhaps with far more dignity than the later "Legacy"). Sure, it was probably part of the series bible, and so "Heart of Glory" or not would have eventually been brought up, and that's part of the reason I give only minimal support to the episode.
It's still memorable. The Klingon death howl is introduced, and for the moment is a hugely significant feature of the society that is just being built around these aliens who are slowly becoming more than just a constant thorn in the side of the Federation. There are more memorable Klingon episodes later in the series, and Enterprise would later feature this kind of kid gloves approach to the Empire (heck, the Bajorans in DS9 are very similar to the Klingons here). At the time this was a very big moment. And it remains one, but its impact has been muted over the years.
Certainly watch it, either as a fan of Worf or Klingons in general. Just know there's better material on the horizon, as with the rest of the season.
franchise * series * essential * character
Memory Alpha summary.