I have an N90. The focusing screen is optimized for AF and is far from ideal for manual focus. You can use the focus indicator dot, but I find it fiddly and not especially accurate. When I want to use manual-focus Nikon lenses I reach for an FM or an F2. The main reason I don't have an F3 is that I find the shape of the little built-in grip extremely uncomfortable, sometimes to the point of being painful. But if it fits your hand, it's an excellent camera.
Originally Posted by joshua029
Also, which FX lenses do you have? If you're buying the latest G-type lenses without aperture rings, anything older than the latest AF bodies like the F100 will allow you only shutter-priority or program AE.