Poor Clancy (unless he wants it that way): been in a million things and, as far as I've seen, only played a non-evil guy once.
I think it's a fantastic existential situation they've stuck Barry in and I was surprised at what an "above standard TV" level the time travel trope was being handled.
I wonder if Barry's thought this all the way through, though. Fictionally, it's no problem at all - it'd actually be kind of weird if he had thought it through because
this is his mom (not to mention saving his dad from years in jail). But, if he succeeds, there will be no relationship with Joe or Iris. No Flash. No friendship with Caitlin and Cisco. It'll be kind of like committing suicide (or mass murder in a weird way): everything that makes Barry Barry will be gone (and everything that makes Joe and Iris and Caitlin and Cisco who they are would be changed, too - those versions would cease to exist according to which handwaving of time travel you used. This is why I hate time travel - it's just wrong and evil and nonsensical. But it's a hell of a thing to think about and the show has a pretty good setup for it.
As far as the episode considered by itself, it was pretty good but I do wonder why the Wonder Non-Twins "have" to leave beyond writer fiat (and I'm glad they did: I was thinking early on in the episode that I liked them being on this episode but that they would screw up the dynamics as more regular characters). I mean, part of the thing was the Prof realizing he'd abandoned his wife and how he was going to be more dedicated to her and then he literally leaves her. And I don't think going to hang out with a known associate of the Prof's is going to keep them "one step ahead" of any pursuers.
And, speaking of, why isn't Eiling dead yet? He's so dangerous and evil and murderous and they just keep punching him. And, again, how long until he's back? He just got carted off so you know he's not dead yet though, by all rights he should be expected to be. But it's TV!
Anyway - glitches aside, pretty good and this is a genuinely likable show.