OK, off the bat, I found this freaking awesome. It had almost everything I wanted in it: Presentation of the main characters, fight scenes, and a cameo or two.
That being said, there were a couple things I'd have to nag about. First off, the introduction of the characters. Sure, each of them have already appeared in the shows they come from, but even so, this kinda seem a bit clunky, as the characters are introduced via introdump, which means that we got a scene that quickly displayed all of the characters being introduced, all in the matter of five minutes or less. If you were a new person to this universe, you'd have no clue what was going on.
Second, the episode seemed too fast paced. Sure it's an action show, but still, the main action scene in it feels a wee bit rushed, This just seemed like a way to showcase each of the characters at the same time. While this was good in theory, the effect seemed a bit off. Side note [SPOILER ALERT!!], we did not get a cameo of Barry Allen/The Flash. Nothing too major, but just a little think that I thought shoulda been there.
Now, done with what's wrong with this episode, let's focus on the good. I think my favorite character in this would have to be Leonard Snart/Captain Cold. For you fans of The Flash, you know that Snart is a villain in the show. However, here he is one of the protagonists, one of the heroes. If you don't understand it, don't worry, he doesn't either. He and his partner Mick Rory/Heatwave both don't get why they were chosen to save the world, but they figure,"Hey it's time travel, why don't we use this as an opportunity?" I find this absolutely hilarious.
Also, the solo action scenes in this are pretty darned cool. While we still have the inrodump thing going on during these scenes, it doesn't make the scenes themselves any worse. Though these little tidbits are just what they are, little, I believe each is a little masterpiece. They show off each character and his [and her] personality.
Also, while many fans of action/adventure dislike slow scenes, this episode handles them pretty well, in my opinion. The slow scenes provide for some very useful information, and even reveal some about the characters that we previously did not know. Also, they allowed for some interesting twists and turns.
All in all, I do believe this was a nice start for this show. The characters are good, the acting great, and the effects awesome. While this has a couple issues, I do not think they detract too much from the episode and make it unenjoyable. It makes me really look forward to what is to come. Hope you enjoyed this and have a nice day!