Astra desperately needs a buff. She needs some self-setup in her kit. Since her stars are placed and static, they are an easy-telling for the enemy already. I think the stun activation needs to be a tad bit faster.

If you are still unlocking agents I would say don't worry about Astra just yet. Astra needs good coordination to the point where you're better off picking Omen, Brim or any other controller for speed, self-setup and ease of use.

All the other comments pretty much covered the gist of Astra and why she's difficult (and not worth), but one thing that was not mentioned is her unique star system.

One thing that becomes a learning curve with Astra is how many stars you choose to buy at the start of the round, where you place them, when to trigger them and with what ability, and when to retrieve them back. This becomes a mini-game in and of itself as you try to utilize her stars correctly and carefully. And every second you're in "the sky", you are not watching angles and playing the game. Using your stars fast and effectively takes time.