Short story:
Yup! By and large, every 2-parter since TBOBW has been a partial misfire or total dud. Save for one, arguably...
Long story:
On one hand, to keep one-upping "The Best of Both Worlds" would be impossible and increasingly incredulous, and always ending on action action action piece would also become tropey. So trying other formats it gets some brownie points for... But that aside...
(Not to mention the music style of the show was taking a big turn, and one that more mimics 24th century life than appeasing the flow and tone of story scenes - a huge risk as the music of TNG was iconic as the rest of the show and now they're doing a paradigm shift for it...)
To the post-TBOBW stories:
"Redemption"'s second part flounders badly, also setting the tone for season 5 (don't get me started on the title logo change, Data's subplot, much less the tachyon net stuff), though pt 1 (season 4) is top tier in blending so many elements.
"Unification" was underwhelming at the time, for both Spock and especially Sela who, in classy season 5 fashion, quickly became a cartoony caricature.
"Time's Arrow" should have been more compelling. At least it's only "mostly forgettable" and not "egregiously bad or plot-by-numbers".
"Chain of Command", which I'd forgotten about until I was about to hit "Post reply", is actually solid, but still feels contrived for (a) getting Picard into peril, and (b) getting the new captain to be as disliked by the clique high school fast food fry cooks bridge crew for the sake of the plot. Almost as cringeworthy as "Ethics" was with the "increasingly evil guest doc of the week just to make a Crusher look good" routine. (By season 5, reusing the same dumb trope of making a Crusher look good by dumbing down and contriving everything else as means to accomplish it... I'll just rewatch season 1's worst stories instead as they handled the Crusher character better, and season 1 has two Crushers to choose from, woohoo!)
Oh geez. I forgot about "Birthright" too... was that before or after "Chain of Command"? Let's see, pt 1 is so questionable with Data dreaming somehow, and letting Dr Bashir ask Data about trying to explain why a human actor is playing a robot about his skin and hair and other navel gazing nonsense, then to wander the ship with an alien gizmo and there's no security protocol stopping him from entering sensitive areas... oh, and then they plug the alien gizmo into the dilithium chamber after hoping the circuit pathway scan is fully and magically compatible with the rubberstamp design-- really, this script is so typical of the era... Pt 2 is better in ways and for a character whose name doesn't rhyme with the second syllable of "panceta"), but it's also worse as it too often feels like it's telling the inverse of the message it's wanting to say but otherwise stumbling at it in every turn, while forgetting other issues because... well, gotta make the bridge crew look good and the guests of the week look bad, wasn't this sort of thing derided enough in season 1 and how come it's not for a character named "Crusher" this week?
"Descent" also has a great part one with much promise despite that style of music that just does not begin to fit or work (but whose use is thankfully limited), but whose cliffhanger - a supreme example of "small universe syndrome" and "fanwank gone wild... to music as orchestrated by a group of farting frogs" was only the beginning of how far "Descent" would descent (pt 2 is so stupid and horrendously atrocious that I'd rather rewatch "Angel One", "Justice", "Code of Honor", etc... especially with the prime beef idea of the Borg becoming individual killers and antithetical to their original M.O. and was effectively chilling for a while, reduced to a dumpster full of cow pies... to music as orchestrated by a group of farting hyenas.)
"Gambit", a surprising improvement as far as 2-parters go, was still so far by-the-numbers (as well as feeling like Star Wars-wannabe as the show was out of ideas and they must have had some leftover script ideas taken from DS9 or something) that the frogs and hyenas watching wondered why they'd spent the effort what with the music orchestrated by a flock of sedated geese with gas problems in this one.
"All Good Things", a couple plot nitpicks aside, was easily the strongest 2-parter since TBOBW and by a considerable distance.
