Notice that the title doesn't say the series hits "all the RIGHT buttons". This is because the series in itself contains a plot so unpredictably executed that at times it's extremely hard to follow what's going on, or to even comprehend why something is happening when it is.
But that's one of the series' greatest charms. The plot isn't all action. It isn't all touchy-feely. It's a well-stirred mixture of both. In any stew, you're gonna have some lumpy bits at the bottom, and this might deter some viewers. But personally, I enjoyed the ride very much.
The animation in the series is superb - extremely well-drawn and easy-to-follow battle scenes, with highly imaginative and numerous protrusions and machinery installed on each robot. The background art is also done to very high detail, and transitions are smooth, with character art also being a defining point in the series. The art is complemented by an excellent original soundtrack, as well as an upbeat set of opening and ending pieces that help set the series' generally tense and excited atmosphere.
There is nothing stopping me from giving a 9 or even a 10 rating except for the arbitrary nature of the series' execution. Although I enjoy the way the animators have fun with the resources they have, it's also quite confusing at times, and it can get quite annoying, especially if you watch several episodes at a time.
But all in all, Valvrave is a defining addition to the mecha genre. Would definitely recommend it not just for the action, but also for the fledgling, yet quaintly humorous romance, and the chemistry between vastly different characters. A solid 8/10, bordering on 9.