Best answer as chosen by user catsinitaly: Advantages and Disadvantages
The Sony NEX 5N has a very high quality sensor, which allows you to take photo in low light conditions without using a flash. However, its autofocus system is slower in low light, and is not as good as a DSLR for fast moving subjects. Also, the selection of native lenses is poor.
You might want to consider the Sony SLT-A57, which looks and behaves like a DSLR. It is roughly the same price as the NEX, but with a faster focusing system and more native (and better quality) lenses.