Let me make this clear: This is a card game-based anime that keeps being a card game-based anime. If you like card games, you will love this series. If you don't, you might either learn to enjoy it, or you won't. The point is that it has consistency and everything that happens and everyone involved tie in together quite nicely. If you want to understand the story, follow the characters, how they interact, and how they relate to one another. You won't get far if all you do is look for some major event that makes the whole show do a total back-flip into a new direction (though, mind you, that doesn't mean something similar doesn't exist in this show *hint*hint*).
I liked the story because of consistency with a slight nudge to the left to keep things fresh. I can't say there was anything boring about the show because when it's slow it's enjoyable and when things are moving in high-gear, it leaves me in supsense. Vanguard was well-written, and kudos to the story writers on a job well-done.
The animation in Vanguard is nothing special, but it's clean, no distortions come to mind, and I can't call it an eyesore in any way. Average is what it is.
Aside from a few in-battle songs (and a pretty cool 2nd OP theme), nothing really stands out in terms of soundtrack. The voice-acting was smooth and well-done, and it was well-casted if you ask me, but I can't say much more than that because I don't think it's my place to criticize Japanese voice-acting.
What complaints can anyone possibly have about the characters? Aichi, the lead role, is an interesting character in how he changes throughout the series, so if your the type of person that likes to see things develop, good for you. Then there's Kai, who's pretty much the ace of the show, so there's your source for wanton destruction as far as card games go. I can keep going, but really, watch the series for yourself and you'll see very few useless characters as everyone has their finer points, and everyone brings something appealing to the table.
What makes Vanguard's story appealing, in my opinion, is character growth and character development. For the sake of keeping your eyes on this review, let's use the main lead, Aichi Sendou, as an example. He starts off as a quiet kid who gets bullied a lot. You either feel sorry for him or you hate him for being so weak. However, he goes through so many changes as a person throughout the series that you want to see where his ambitions and goals will lead him. And they do lead him to places you would'nt expect.
This doesn't mean that every other character is a bland and typical archetype with no depth. Like I said, everyone brings something interesting to the table, and it will be hard not to find a favorite character in somebody.
I summary, Cardfight! Vanguard is an enjoyable series that doesn't deserve the harsh reception I've been seeing it take. You have to watch it with an open mind and for God's sake, stop comparing it to Yu-Gi-Oh! because at least Vanguard tries hard not to oversell and it stays true to the actual card game it was based on the whole way through. That's the biggest problem with all the reviews I've seen so far; all I've had to do was look into the paragraphs and see if the word Yu-Gi-Oh! pops up and I know I don't want to read it.
If you want a series that's about card games, and the experience of being a fan of a card game, then watch Vanguard. It's genuinely the best in terms of reflecting the world of card game players, and of course, it does what's necessary to keep the audience entertained, which I thought it did to a tee, but I guess everyone's too caught up with comparing it to Yu-Gi-Oh! to see it for what it is: Awesome.