I'd be in a very bad situation if I was asked to give a summary to this, just know it's about time travel. That much I understood.
As usual, characters. We've seen only 4 for now so I can't really say much, just that they're weird, and that I already love the mad scientist and the hacker. Especially the mad scientist, he's truly mad. Not only like a usual mad scientist but he's insane and paranoid.
The two girls, well, I can't say much about Makise we've seen her 3minutes or something but I don't like the other one, I don't hate her either, so yeah, just don't care.
The version I've seen didn't have the OP nor the ED so I can't say anything. I actually haven't noticed the music which is a good sign, it means it fits.
As for the cast, I've been surprised by Mamoru Miyano, I totally didn't recognize him at first. Kana Hanazawa on the other hand has another cute-but-hyper voice, like Nessa in Fractale. I'm a bit worried I'll overdose, she's good and I love her but she's voicing at least two other main characters this season, but it has nothing to do with Steins;Gate so I'll stop here.
Now the anime in itself, I don't think I understood what was going on very well. Time travel is hard for me to grasp, especially when the characters themselves don't know what's going on.
Oh well, I like the dark atmosphere and it seems it'll be the serious kind of anime, with a bit of nonsense added to the mix.