One of the nice things about a DSLR camera is the ability to change lenses.
Understanding Camera Lenses
Any lens with a 10x+ focal length zoom range is also known as a 'superzoom' lens.
18 mm to 200 mm is an 11.1x focal length zoom range.
Computers allow designing lens with such an extensive zoom range, but even using computers a series of design compromises have to be met in order to keep the cost of the lens reasonable.
All those design compromises deliver a lens that is convenient to use because of it's 'superzoom' focal length range, but the design compromises diminish image quality in a variety of ways throughout the zoom range. How image quality is affected varies by the lens make and the focal length used, but all of the 'superzoom' lenses have image quality issues of various types - soft focus, chromatic aberration, barrel distortion, pincushion distortion, and more.
For most amateur photographers the convenience of a superzoom lens is the primary reason for getting the lens, and the image quality issues are of little concern.
Indeed many amateur photographers aren't aware of the specific image quality issues. All they know is that their photographs are good enough for their purposes.
Had you asked about what lens to get, many here at TPF would have recommended 2 lenses that together have the same focal length range - an 18-55 mm kit lens and a 55-200 mm kit lens.
Here is the Conclusions page from a respected web site that tested that lens:
Canon EF-S 18-200mm 1:3.5-5.6 IS review
Canon users will perhaps most wish to know whether the 18-200mm is a good replacement for the
EF-S 18-55mm F3.5-5.6 IS and EF-S 55-250mm F4-5.6 IS kit lens combination. The primary advantage of the superzoom is simply that it eliminates the need to change lenses; it's also somewhat better built, and has a non-rotating front element which is an advantage for filter users. But the two-lens solution gives longer reach, and (although we've not yet formally tested the 55-250mm) we'd expect it to give nothing up in terms of optical quality; the overall weight is near-identical too. So overall, the answer isn't necessarily clear-cut.