Body Elements

The E-M10 looks a lot like the E-M5 - featuring a similarly angular 'prism' hump but, unlike the more expensive model, the M10's hump houses a small flash.

It's not a terribly powerful unit, with a Guide Number of 5.8m at ISO 100. But it does allow remote control of external flashes, such as the comparatively affordable FL-300R.
The rear control dial sits on a raised platform, giving a little more separation between the dial and other controls. The front dial is close-by, and easy-to-reach with your index finger.
The viewfinder is essentially the same as that on the E-M5, offering a large, 800 x 600 pixel view. It's not as high resolution as the E-M1 (or the higher-end cameras from Fujifilm or Sony), but the 'adaptive brightness' system makes it nice to work with.

As with the E-M1, the M10's eye sensor is disabled if you pull the rear screen away from the body - a little detail that makes a big difference to usability.

The mode dial on the top plate has the usual Olympus options, including iAuto, Art Filters, Scene modes, and 'Photo Story'.

One feature unique to Olympus is that any of the mode dial positions can be assigned to recall a custom camera setup (or 'MySet' in Olympus parlance).

Under the mode dial is the release for the pop-up flash, which is quite difficult to get at. Next door to that is the diopter adjustment wheel for the EVF.
The rear controls of the E-M10 closely resemble those of the E-M5 but, presumably because they're not weather-sealed, they feel more responsive (rather than exhibiting the slightly spongy feel of the E-M5).

The power switch is in the same slightly awkward position as the E-M5's, at the lower right of the body.
The I/O ports are under a rubber cover, and include USB + A/V output and micro HDMI.

The USB connector also accepts an electronic cable release (Olympus RM-UC1 or third-party clones).

The battery and card are located in the same slot on the bottom panel, which is less convenient for tripod work.

And, although there's little difference in size between the two, the E-M10 uses the 7.8Wh BLS-5 battery as used in the PEN series, rather than the 9.3Wh BLN-1 unit from the other OM-Ds models.

The result is a 320 shots/charge rating, according to standard testing.