Be aware that this lens gets pretty slow once you start reaching the higher focal lengths. Anything past 100mm is at f5.6.
Focal length - Max aperture
18mm - F3.5
35mm - F4.2
50mm - F4.5
70mm - F5.3
100mm - F5.6
200mm - F6.3
270mm - F6.3
IMO, you would be better off IQ and speed wise to keep your kit lens and add the Canon 55-250mm f4-5.6 w/IS. And for the price difference between the two, you could pick up a used older body to mount this lens to if your worried about having all focal lengths covered at once.
I once lusted over the 18-200/18-270/28-300, but quickly fell in love with the renderings of faster glass.