As I am still a Sony user (currently moving to Canon) I guess I should say a few words about Sonys lineup.
First of all, the sensors produced by Sony are great. The only issue is that used in Sonys bodies the noise performance is pure crap. If you compare high ISO performance of any Sony camera with the counterpart of Nikon, you will see how miserable NR is. The newly released A57 however seems to be changing that quite amazingly.
As far DSLTs and the A77 are concerned - yes, what you mentioned here is absolutely true. You basically have a camera which is designed for fast action, but the EVF with its lag simply kills this advantage. Another one is that due to the translucent mirror you get 30% of light to the AF and EVF and 70% to the CMOS sensor. This has IMHO two main disadvantages - less light on the sensor means reduced IQ and less light to the AF sensor means poorer AF accuracy, especially in low light conditions.
Last not least - what is the main issue for Sony is their pricing policy. They outprice themself in the market. Tha 500mm f4 is just the latest example, where it would be cheaper to buy a D800E with the Nikon 500mm and still would save you a few grand. There are quite some holes in the lens lineup, but Sony keeps releasing bodies way too quickly and is very slow in releasing lenses.