You have to make sure to get the model that says for Nikon w/ built-in motor, for the D40. Forgot to mention it does feel more solid than the kit lens and it's also heavier. Most other options would be even more solid and yet heavier, so I think it's about perfect for the D40. It makes it look and feel more serious, if you know what I mean. As for it being a great portrait lens, the glass is sharper, but also keep in mind (as I mentioned) that you can go as wide as f/2.8 at 50mm, while a kit lens is stuck at f/5.6 and you need to stop down to probably f/8 to get a sharp shot, at which point, if the background is close to the subject, it will be in focus too, which can be distracting (depending on the background). With the 17-50, you get good sharpness at f/2.8 but even better at f/4 which is a more typical portrait aperture, plus your background will still be blurred (which is usually good).