I think of this as being like Evangelion Light meets Charlie's Angels. 3 young girls are purposely sought out to pilot a prototype military mech and experience the trials of bonding, training, and earning the respect of their ranking superiors.
Very similar to Evangelion: Years ago humanity fight the WORMs, the race is on to develop the mechs in anticipation of the return of the WORMs, mech's fight the WORMS. I thought the first half was superior with lots of slice of life stuff with the girls getting to know each other. The second half revolves around battles and I found the odd episode to be lacking in anything of interest or entertainment.
Very good. The use of CGI isn't intrusive. The backgrounds are good-looking. The characters are all very distinctive, fluid, and the girls looks suitably cute. The action scenes are very exhilarating with a real feeling of the g-force while their hurtling through the skies.
The group dynamic is fantastic. You've got the bookish one, the hard-ass, the playful one and later on the stuck-up immature one. They all quickly get their peers and the audience cheering them on. The show is always tasteful and is resists being leering.
The soundtrack really does a good job of complementing the show. It plays out in the background adding ambience or excitement without drawing attention away from the action. The tunes are memorable, particularly the string arrangement that plays in the first half of the series during the flight sequences.