One of the better "Companion's First Adventure" episodes, and sets up pretty much all of Clara's characterization but still flawed and hampered by the production disaster that was S7.
For me, it’s neither good nor bad - just very forgettable. I’ve watched it numerous times over the years and still can’t really remember that much about it.
I think it’s a good episode mainly for the reason that it’s quite like a classic episode. You could easily place this episode in Tom Baker or Davison’s era. The nostalgic feeling cancels out the fact a sun-god was defeated by a leaf.