I liked it for the most part.
I still think the concept of the Guardians of Time is pretty naff. What do they actually do eh? If the White Guardian is so powerful he can pluck the TARDIS out of the vortex, why can't the Black Guardian? Kudos however to Tom Baker's restrained performance in those scenes as it highlights just how much of a powerful being the White Guardian is supposed to be when given this due deference. There is though that wonderfully understated lin where the Doctor wonders about the conseqences of refusing to gon the quest. "Nothing."
Romana makes an interesting addition to the TARDIS crew and there is a lot of comic potential for her relationship with the Doctor. This is only my second viewing of this story (indeed of this season) and so I am more used to the Lalla Ward incarnation. Mary Tamm does a good job of making Romana likeable inspite of the antagonism suggested by the script.
Good performances from all of the supporting cast but particularly Iain Cuthbertson as Garron and Paul Seed as the Graff Vynda-K.
I know we shouldn't try to be too harsh about the standards of special effects but the Shrivenzale.... oh dear. Can there be a worse Doctor Who monster? Ok yes I know the Taran Wood Beast will rear its ugly head later this season!
A fun little opening episode and look forward to the rest of the story.