Weidian is legit. Just like any other marketplace, the biggest factor are the sellers, and you can't speak for them all.
Weidian is known to have more of a hands-off approach when it comes to setting up a store, which has many benefits, but it also means that there are no big deposits that keep sellers from scamming.
That's why it's definitely recommended to use a shopping agent. This also helps you with the fluctuating quality Weidian is known for.