I've been thinking about grabbing a pair myself and so I'm also curious what actual users have to say.
In the meantime here's what I've found. Overall, the Nothing Ear earbuds' microphones get solid marks for clarity, especially on the 2024 model, and they do a great job on calls.
Some say in really busy places you might hear some background noise, and a few users have had one earbud struggle to pick up their voice, so if that happens, you’d want to reach out to support for a replacement.
All in all the mic performance is good, but just keep in mind there can be the occasional hiccup.