Preteens dramatically playing card games is a surprisingly popular genre of anime.
Shadowverse is based on a mobile game that’s popular in Japan. It’s fine. It’s obviously for kids, but it’s not bad. It’s a little contrived – honestly, what kinda kid bets their phone on the results of a card game? – but it’s fine, for what it is.
It’s no Yu-Gi-Oh, but kids’ll probably like it anyway.