Apple are usually good these days with acoustics but the smaller form factor may result in a louder device at high workloads.That's the thing I'm waiting for. Reviews about how loud this thing is (if at all). I currently have an M1 Mini, and I don't ever hear the thing. It'd be weird if I suddenly started hearing fans again like it was 2008.
My concern is more about dust accumulation. The trend with ARM and its efficiency is towards more passively cooled devices. See the newest Apple TV and MacBooks for example. They are quiet, have fewer moving parts and so are longer lasting. However it appears they have prioritized power over that here. It would have been nice to have the Mac mini become a passively cooled device. It was never meant to be a Pro device in any case. It was always an entry device and device for those wanting the smallest possible and quietest desktop form factor.