One class of MILS cameras, made by both Panasonic and by Olympus is called the Micro Four Thirds cameras. They all share is the use of a 4/3 size sensor that is slightly smaller than the APS-C sensor used by Canon and Nikon. Using the M4/3 sensor results in a crop factor of 2.0 for lenses. The kit lens is a 14-42mm lens which has the same field of view as a 28-88mm on a camera using a full frame sensor. The first m4/3 sensors were 12 megapixels in resolution. The later models have stepped up to 16 megapixels. And you can interchange Oly and Panny lenses from one brand to the other. With the proper adapter you can also hang almost any camera lens on a micro-4/3 camera. When you use an adapter, you lose the auto-focus function. I have several Pentax K-mount lenses that do a great job as manual focus lenses. There is a complete suite of auto-focus lenses made by Panasonic and Olympus that fit the M4/3 cameras.
I own a Panasonic G2. It looks very much like a small DSLR but when you use the viewfinder you are actually looking at a small electronic screen. Like with a DSLR, you see the camera settings as well as the subject that you are photographing. The M/43 cameras take excellent videos as they have full time autofocus in the video mode.
When you are using it with non-M4/3 lenses and are using manual focus, you can get an enlarged view through the viewfinder to assist with manual focus. Although one can use auto-focus lenses of other brands (with the proper adapter) it is difficult to set the f/stop of an auto-focus lens because AF lenses don't have an aperture control band on the lens. Most older manual focus lenses have the control band and it is very easy to set the aperture. One additional thought about the MF lenses is that they are very inexpensive and it is also easy to find "fast" lenses. As an example I was able to acquire a 135mm f/2.8 lens for only $25.00.
Some photos of my G2.
Here is a photo of my G2 with a K-Mount 70-200mm Promaster mounted on it.
Here are some photos taken by the G2 with a Pentax 50mm, f2.0 mounted on it.
That is about it until I take some more photos. Have a great summer day.