But you know how this is being spun. Fine upstanding FBI leader thinks evil Trump is a liar! He was fired for investigating him!
That part appears to be somewhat true.
I've already seen the headlines saying he made the concrete case that Trump obstructed justice.
That part's not.
Those two things are not equivalent. I think Comey's testimony did a lot to quell the "big scandal" Russia conspiracies, and specifically that Trump didn't try to "obstruct" any investigation, but at the same time poured some gas on the "little scandal" that he did fire the FBI director for no good reason other than him not "being loyal" enough to make a big public show over his non-involvement in the Russia investigation at that time.
The conversations he did have with Comey, while not technically "obstructing justice", were reminiscent of Lynch's conversations with Bill Clinton on that tarmac though. Nothing technically illegal, but also unseemly and not something you want to hear from someone involved, even if indirectly, in an FBI investigation.