I have a 750 and a 60CSx. The 750 is a bargain at that price, I paid a bit more for mine last summer. It works really well, as long as you don't need to have integrated bluetooth and radio traffic reports included in the same unit.
One of the best things about the 750 is that it is the least expensive Garmin unit you can get that will allow you to build and save routes with multiple waypoints using just the unit itself (as opposed to creating a route in MapSource on a PC, then uploading it to the device, like you can with a 60CSx). With the lesser ones you are stuck with only being able to specify the start and finish points (or, on the really low end ones only the end points) and having Garmin pick the route for you. This worked great for me on our last road trip since I was carrying a MacBook instead of a PC, so I could not connect to my 60CSx.
I am very happy with the 750 for auto navigation. The only thing I miss from the 60CSx is the altimeter. The maps are identical if you buy City Navigator and upload it to the handheld (60CSx), but much easier to see on the wider, brighter 750 screen. The voice prompts on the 750 are satisfactory. I find the American girl's voice somewhat annoying, so I use either the English girl (Emily) or the Italian girl. One time when I was not looking Heather switched it to the French guy, but that did not last long.