Canon EF-S 55-250mm f/4-5.6 IS Telephoto Zoom AF Lens for Selected Digital SLR 4.7 out of 5 stars (131)
I've just purchased this and whilst I've not done extensive testing (only had the camera and lens a day) on it it seems to perform well. As it is an older lens, the leaflet in the box will not mention that is it compatable with the 600d, but it is!
Edit: Now I've had the camera and lens for a couple of weeks or so and been out and about with it, I can say that for the price the lens is a great buy! I'm still learning with this being my first DSLR but I've already had some great shots from it. I tend to shoot mostly in AV prority.
I was thinking of getting a new lens too to compliment my 600d with the 18/55 lens. So u think the 55/200 is next best?. I'm a novice to be honest but I do like the fact that most comments are very good and there doesn't seem to be any lens creep with it either.