D90's a fine camera. If I remember, you already have a Nikon body and reasonably good lenses. I'm not sure the D90 will necessarily make your photos better. Again, if I remember, didn't you buy then sell an SB800 when the SB400 would have been a better match? But anyway, the D90's a very good camera with no real vices. Better dynamic range than many of its competitors, at any price, when it was released. In terms of "can it guide me to a better photo", you might want to look at the D3000.