Sony is lacking in a few areas
- Lenses. While they do offer lenses that 90% of users are looking for there are a few gaps either in offereings or quality of those offering. Like a 24-105 f4 Pro level, any type of tilt shift, 400mm f2.8, some of the lenses are older Minolta designs. Most of these older lenses where deisgned for 35mm film as a result lack modern coatings and can suffer from flare and chromatic aberations. Other lenses are simply behind the quality of the equivalent of their Canikon counterparts. Ie the 70-200mm f2.8
- Wireless flash control. Sony has simply continued to use the Minolta wireless. The Minolta system was ground breaking when it was introduced. Unfortunately it hasn't been supported or updated by Sony. No IR controllers. The way you have to mount each of the flashes to the camera before using them wirelessly. The way the controlling flash can not be set to not contribute to exposure. (This can be done with a single flash controlled by the pop-up flash, though you'll not find it in any manual) Why Sony doesn't advertise their system is beyond me. Most people let alone most Sony users are unaware that Sony supports wireless 3 channel ratio-ed TTL off camera flash support.
- Pro/Serious Amateur support. Currently Sony does not offer any full frame cameras. Sure the A99 is rumored to be announced soon, but we have heard that for 6 months now. While I'm sure at sometime we will see a FF camera, will it be up to the quality of the Canikon offerings? I am certain we will never see a true pro level camera equivalent to the 1DX or D4. When a FF camera comes out will it have a solid selection of Zeiss and G lenses to go with it? What this means is a lack of upgrade potential for users.
- EVF/ SLT While this is a point of contention I feel that the EVF is a great upgrade from a small dim penta mirror system offered on consumer level camera from Canikon it really can not replace a large bright penta mirror. The A900 had the largest brightest OVF of any DSLR camera. That will be thown away. The lack of dynamic range that can be displayed in a EVF will never be able to compete with a quality penta prism with a transparent LCD overlay.
Bottom line is Sony is competing for the lower end of the market. Entry level customers. There they are very competitive