The trouble with "Unification" is that.... well, it set itself up as, ironically, a show that was self-prophesized to be EPIC, but wasn't. To be sure, it wasn't the first time TOS characters had appeared on TNG. But this was
Mister Freakin' Spock! Arguably *the* most iconic Star Trek character of all time bar none! But what got presented to us were two middle-of-the-line episodes that had some cute character moments, but didn't really capture the zeitgeist that they hoped they would. I say this respectfully, but Nimoy's performance isn't at his best here either, he
clearly wasn't invested in the material he was being given, and it shows on screen. I
strongly suspect he only did it because Rick Berman presented it to him as a way to cross-promote Star Trek VI, and as producer on that movie Nimoy thought it couldn't hurt.
As much as "Generations" was an anti-climax as a story (and it
was, make no mistake about it), at least they managed to wring
something out of putting Jean Luc Picard and James T. Kirk on screen together, even if it was just the Odd Couple aspect of the two of them being very different characters while making an omelette together.

"Unification" doesn't even give us
that much.
Curiously, I'd say that "Relics" manages to be everything that "Unification" wasn't: a joyful celebration of both TOS and TNG by all concerned, feeling like they were actually invested in making this the special event they wanted it to be. It bridges the two shows beautifully, celebrating their differences while solidifying the things they share in common, and it provides James Doohan with perhaps some of the best material he ever got as Scotty. It's a gem.
