A lot of people dislike it for the privacy nightmare that it is and feel the threat of an EEE attack. This will also probably not be the last time that a big corporation will insert itself in the Fediverse.
However, people also say that it will help get ActivityPub and the Fediverse go more mainstream and say that corporations don’t have that much influence on the Fediverse since people are in control of their own servers.
What a lot of posts have in common is that they want some kind of action to be taken, whether it’d be mass defederating from Threads, or accept them in some way that does not harm the Fediverse as much.
What actions can we take to deal with Threads?
That’s what they want you to think. (not sure if I’m being sarcastic or not)
Even if that’s true, once they become a part of the ecosystem, they will start looking for ways to dominate it. That’s just the nature of for-profit corporations.