I think the idea of it is pretty smart, Instagram probably has a lot of shared users with Twitter. If the quality of Twitter decreases then Instagram making a competitor seems like an easy win, especially if the issues plaguing Twitter aren't plaguing Instagram. The privacy concerns due to required permissions are probably the most concerning, but if you were using Twitter and Instagram you're probably not even considering that.
I'm definitely not going to try it, but I kinda hope Twitter completely busts at this point. Elon's next autobiography is going to be, "The Art of the Deal 2: How I won by losing $44 Billion."
As much as I hate Meta and hate Twitter, more competition between them is a win imo. It also helps break the mindset of people that there aren't any alternatives to twitter, which makes them more likely to try things like Mastodon.
If I use it it'll be from a federated fediverse instance after Threads connect to it. I'm not running there, but I genuinely think it's better that it exists.