@Superku: It depends.

The problem is, that it's not easy at all to create good normalmaps.
Especially generated normalmaps f*ck up the results.

When created and used properly they can increase the visual quality pretty much.
...but in the most cases users just use a generated normalmap from the actual texture - which is the worst normalmap you can get.

(heelx' normalmaps from the previous page seem to be really good, just to give an example)