If you want to laugh, cry and be surprised over and over again, and if you like anime where every character has character, becomes an important part of the plot, and develops throughout the series, this is for you. Here is a great series that has a serious message, but doesn't take itself too seriously either: the humour is Always there, but (most of the time) it doesn't ruin the immersion, fortunately.
The plot and "scheme" is deceiving and surprising, and it actually makes sense unlike with Digimon. Everything that happens fits in. That's all I can say without major spoilers. Compared to all Digimon seasons, which I have regrettably watched, this series has far, far superior plot and characters, and the Legendz are the main characters (more and more throughout the series) and make the majority of the meaningful decisions in the anime. I cannot explain all the differences without spoiling the plot but let's just say, the series is NOT what it first seems. As far as I understand, the manga pretty much does not have anything to do with this anime, on many levels - fortunately, as the manga isn't very good as far as I can tell.
That being said, you might (probably) not like all the characters in the beginning, and the art style probably seems childish at first when it comes to the human protagonists. The very beginning of the series (especially the first half of episode 1, and the first two episodes) will probably make you question how special or good this anime is going to be - but after that, the humour (ep.3) and plot really starts to kick in. Plot-wise, in the episode 13 your jaw may drop. Whatever you do, don't drop Legendz because of the first two episodes - practically zero plot background is given in those two episodes, but everything that happens makes sense in the end.
And that's the thing with this anime; half the time you're expecting something completely different, and then something absurd or serious happens. And even still, some things you would expect and hope to see, and they will happen eventually. The beginning episodes of this anime probably seems shallow, but like I said, this series is surprising over and over again.
The music is.... pretty damn good. There's only one opening, and at times, it feels too cheerful for the series, especially after main plot turning points - but the ending (Dounimo Tomaranai) kicks major ass. The in-series soundtrack is swing and jazz/jazzy, at times smooth, at times lively, and groovy cheerfully upbeat in the action sequences (also with epic synth sections that you cannot find in the OST, that play in key battles/turnpoints) - overall, I would say "atmospheric", as the plot happens in Brooklyn, NY.
Despite having actual plot, there is no excessive, out-of the place drama - which makes the series more realistic and approachable. When the drama happens, oh boy, is it dramatic - and then again, unexpected humour kicks in. I adore this series both in its golden character interaction and surprise factor, and lack of meaningless drama.
Overall, this series is very heartfelt, interesting (throughout the series, amazing achievement) and enjoyable, without going overboard on any aspect (except for silly humour with Shuu in the beginning episodes). Whatever you do, don't skip this one because of the first two episodes - this anime unfolds itself in very surprising ways, and the character interaction (including all the voice acting) is superb. I really recommend this one.
