The new craze of mirrorless cameras, blow my mind!!(The iPhones of profesional cameras if you will !! Assuming you're an iPhone fanboy?!)
All brand systems will eventually abandon the bulky, aging, DSLR style; since a large portion of the mass it is a dated, "hold over" form the days of 35mm film. Just a silly premiss, given the digital age.
The only reason to go another, more "traditional" / mirrored route at this point, in the DSLR arena, is if you have an existing, extensive, past investment in old lenses and accessories. (Or you are shooting in a controlled environment, such as a studio or some other rare profesional demands.)
If not, the mirrorless, current tech (which avoids the old, film based, internal designs methods,) is the most exciting, exceptional option. Less is more in the case of camera technology and eliminating the middle man, a mirror which use to be needed in order to reflect an intermediary version of what the lens is seeing while the light is on the way to the sensor or the film is simply no longer a required step.
Less parts, or NO MIRROR as it were, makes your camera faster, leaner, meaner! Makes the preview image you review, during each shoot more advanced, more accurate, more true to the settings and goals of the intended shot. There is less chance for light leakage, additional cleaning and dust issues, and more chances for superior picture taking.
GREAT for an active folks! Folks that travel! Folks that love photography and videography. Much easier to pack and have handy. Much more shot reliable. And the BEST camera is the one you have with you! The one ready to take the shot.
(plus they really are the best, latest technology!)
Reviews, specs and Videos:
NEX7 - (Shot w/ the camera) http://goo.gl/MpMuh
NEX7 - Artsy Foreign Comercial: http://youtu.be/lbKrd2nchgU
Sony Site - http://goo.gl/sp13o
Sample Movie, shot with NEX5 (all lighting types):
Very cool leather "half case": http://goo.gl/VJQWV