I didn't like how happy everyone is and how fast the crew bonded in the first season. The music is next to terrible. It is grand and optimistic and every scene feels like a trumpet before a king enters his court.
The second season ditched the bad music and the happy faces all the time. There was actual exploring going on. REAL strange, new worlds. Pulaski is my favorite doctor outside of Bones, and I really enjoyed her scenes (especially with Data). It built his character. There weren't cheesy story lines with Wesley as there was in the first season. "The Measure of a Man" and "Q Who?" remain greatly written episodes. The only season finale I hate, Shades of Gray doesn't do justice to the performances they had throughout that year. Season 2 is my 4th favorite season and it's a big distance between 4 and 5.