I've always thought Gambit was the worst two-parter. It's so slow and boring. It easily could have been trimmed down to one episode.
Gambit, Descent and Birthright are snoozefests that I usually skip.
TNG got weaker with each of its season cliffhangers. BOBW was excellent, Redemption was good, Time's Arrow was OK, and Descent was meh, IMO.