The A7 engine itself isn´t that bad at all. It´s quite competitive with Unity in my opinion (except maybe the ODE physics engine and lite-c, which is a less modern and less sophisticated "scripting" environment than MONO). The tools make the difference. The Unity editor is what a game editor should be like nowadays and Unity comes with ready to use high quality solutions for things that require a lot of your own work in A7 (shaders and shadows for example).