I have just been thinking, and have noticed something. Is it just me, or does enterprise seem crewed by a bunch of miserable farts.
When I watch TNG, I can easily see that the crew actually enjoys their job .... they are having fun romping around the galaxy in their starship. You can feel it in the way Patrick Stewart plays the captain, almost every time he says "engage", you can tell that Picard can't wait to find out what is around the next corner. Same with most of the other characters. Their enthusiasm is infectious and it draws the viewer in.
On the other hand, Enterprise seems like the exact opposite. The captain has barely smiled in all 4 seasons, he seems like he is only on the ship because it is his job. The other characters are hardly any better, with only the doctor ever really showing any joy in his work. Sure, they take a lot of pride in their work, but there simply isn't any fun.
It was only really the mirror episodes that showed this difference to me, because unlike most eps, the crew of enterprise seem to be at least having some fun.