Over a year ago, I couldn't really see myself using a mirror-less camera model. I have been good with a dSLR, and I didn't feel any need to switch. The various new system cameras didn't offer me anything great, until the GH3.
Now, it's easy to see that the Panasonic GH3 is the size of a smaller dSLR, but with a well-proportioned body and good grip. The designers actually thought about its being used by photographers. Isn't that amazing?
Add to that reasonable still photography and incredible video photography at a reasonable price with weather-sealing, and you've got a recipe for taking on a hurricane. I know--I've been out in hurricanes, photographing them with the Olympus E-1.
I was stubborn that an electronic viewfinder could not work for me and I wasn't going to use the rear display because of the trouble using it in bright sunlight. I was half right.
Using a rear display doesn't work well in bright sunlight, but the smaller EVF can, especially those of the Olympus E-M1 and FujiFilm X-T1. I haven't seen the Panasonic GH4's improved EVF but I expect it to be good, not great. I have various issues when using the GH3 viewfinder, mainly with sunglasses, but it is relatively good. I've used the Olympus E-M1 extensively and found that it doesn't seem to have the GH3's problems, and since many people have commented that the FujiFilm X-T1's viewfinder is even better than that of the E-M1, I would say that my short experience with the X-T1 would be very positive and typical also.
Where the EVF shines on the GH3 is at night. I can see to frame and focus in ways that an optical viewfinder does not work well. I had great respect for the Olympus OM-1N viewfinder--the brightest in the business at the time, but the GH3 does miracles for night work, and I'm guessing that any EVF can work similarly well.
Along with that, the GH3's auto focus works to EV -4. That's equivalent to starlight. I took some quick photos after the firmware update, just to see, and it worked incredibly well. I hated the image quality, as I wasn't really trying to do anything important and didn't plan, but it worked.
The one thing I dislike with the Olympus E-5 and Nikon D7100 and Canon 70D users will understand: switching to Live View takes a fast camera body and makes it seem horribly slow. There were occasions when I flipped out the display (don't try that with the D7100 or 70D!) and enabled Live View and it felt as though time stopped. I got the photos I wanted, and it's so nice to be able to point the lens upward, while looking at a comfortable angle, but you have to be a bit patient.
The GH3 allows me to switch back and forth quickly because the same feed and the same auto focus is working. Since there is no optical viewfinder, the imaging sensor is working in Live View mode all the time, and it's made to handle the thermal stresses, as well. Need to hand-hold a Live View shot at a steep angle in portrait orientation? The GH3's rear display can do that for you, and you will still be comfortable.
There was a time when I would be flat on my back, looking up at a building, working to get a certain vertical shot. I no longer have to do that.
I was taking some photos last Saturday at an arboretum and park and it was simple to get each shot. I thought that the rear display would be unusable, but I could actually see it fairly well. Someone asked me to take a photo or two with their smart phone, and I was surprised at how poor the Samsung Galaxy S4 display did in bright light. I could barely see where the shutter release button was. Considering that Samsung uses their phones to showcase their displays, it was disappointing. I had new respect for Panasonic.
I know, better than most, what speed means. After all, I photograph a lot of sports. I can understand why photographers have switched to video for cross country and track events but I have not. I'm still sorting things to use the GH3 in such sports, although replacing it with the GH4 will likely help, and that's on the list. I don't do a lot of burst mode shooting, but 12 frames per second sounds better than 6 frames per second when it comes to crunch time, don't you think? Of course, auto focus had better work well also, or you'd better be able to manually focus the lens quickly. (I'm good with manual focus on dSLR lenses because they're big enough for that to happen. micro Four-Thirds lenses are tiny, in comparison, so I require auto focus to work well.)
The only thing you can't fix with mirror-less equipment is the price. I pick and choose but on the whole, everything that will get you high image quality is really expensive. Mind you, it's often cheaper than equivalent dSLR equipment, especially weather-sealed equipment, but most people don't see that. Once again, photographing hurricanes, the weather-sealed equipment worked beautifully, and every time I shoot cross country in the rain, I giggle at the people trying to hide their equipment from the downpour.
I know that dSLRs will go away eventually. I'm sure everyone realizes that. I was stubborn and didn't want to let go but suddenly, with the right lens, I'm realizing the benefits of mirror-less technology.