The Canon XSi has many upgrades from the XTi. For starters it has a: Digic III Processor, Live View, 3.5 frames per second, 3" LCD, 12 megapixels, bigger viewfinder, better grip, upgraded kit lens, and spot metering.All of these things mentioned above are very nice. They provide an entry level camera with advanced features. The only negative I can think of for this camera is that it uses SD cards instead of CF cards so if you have a collection of CF cards, you are going to have to sell them and buy SD cards. The bigger viewfinder was a big relief, because on previous Rebel cameras, the viewfinder was very small. The new grip is also a very nice upgrade rubberized as it uses a ruberized grip. Also new to a Rebel series camera, it features a dedicated ISO button for easy access and also displays the ISO setting in the viewfinder. Also this camera has a live view mode. Although almost every point and shoot has a live view mode, DSLR's are just starting to get them. Live view is being able to see the shot in a live time on the LCD screen. It can be very helpful for shots with angles that you simply just can't look through the viewfinder. Another improvement that is liked by all is the addition of an upgraded kit lens. The kit lens that came with the XT and XTi, the 18-55 f/3.5-5.6 was a terrible lens and was not very useful. The new kit lens is the 18-55 f/3.5-5.6 IS. It provides image stabilization and better optics. The larger LCD is also a very nice upgrade. Spot metering is a feature that has never been in a Rebel series camera before and is greatly welcomed in this camera. Although the price is on the upper side of entry level cameras, you get more than just an entry level camera, you get a camera with advanced features.
Hope that helps!
