Preorders:
OM-1 at BHphoto, Adorama, Amazon. GetOlympus.
OM-1 in EU at Calumet DE. Fotokoch DE. FotoErhardt DE. Wex UK. Olympus DE, Olympus UK, Olympus FR, Olympus IT, Olympus ES. Olympus NL. Olympus BE. Olympus AT. Olympus CH.
40-150mm f/4.0 at BHphoto, Adorama, Amazon. GetOlympus. Calumet DE. Wex UK.
12-40mm II at BHphoto, Adorama, Amazon. GetOlympus. Calumet DE. Wex UK.

PcMag concludes:

Photographers with a big stash of Micro Four Thirds lenses had some heart-skipping moments when Olympus spun off its camera division. But OM System has already put photographers at ease with a quality lens, the 20mm F1.4 Pro. It’s early days, and the OM-1 is just starting to ship to photographers, but our time with the camera has already shown it to be a big step forward for the Micro Four Thirds format. Time will tell if it’s remembered as well as its legendary namesake.

In terms of handling, the camera’s build quality is a tick up from the last generation of Olympus cameras—buttons feel better and the viewfinder is a big improvement over the one on the E-M1 Mark III. We also like the refreshed menus, which are a bit easier on the eyes. The sensor and processor upgrades make for snappy response all around.

But there are a few disappointments. We’re happy that OM included so many subject recognition modes, but autofocus isn’t completely reliable, and you need to tell the camera what type of subject you’re targeting. The $2,200 price isn’t totally out of line for such a capable camera, but it puts in the ballpark of full-frame models like the excellent Canon EOS R6 ($2,499), and well above the $1,700 Fujifilm X-T4, our current Editors’ Choice winner for less-than-full-frame mirrorless cameras.

Ultimately, if you’re using an E-M1 series camera, the OM-1 is a significant upgrade and still takes all of your Micro Four Thirds lenses. It’s also an excellent option (and system) if you care most about portability.