Judging by the high rating and ecstatic reviews, I'm more lukewarm on this episode than most. This isn't a particularly "heavy" episode intellectually or emotionally, but it does offer plenty of entertainment.
The writers clearly had fun fooling around with "what if" on this episode, throwing in increasingly bizarre/absurd twists. Data's blue eyes, the marriage to Counselor Troi, the changes to the bridge's look, Wesley as an officer, and finally the scene with the many Enterprises. That scene really is the highlight of the episode - played for laughs (285,000 hails!) and drama (the Enterprise from the Borg universe).
Among the best of the uneven 7th season.