The 55-200 is a good telephoto lens to start out with, because it's cheap and lightweight, but that's about where the advantages end.
In my experience, it was a bit soft in general. The autofocus is old tech, slow and noisy...disadvantages, disadvantages, blah blah, whatever...the point is that a little edge softness is the least of your worries.
Also, there are very few lenses with no sharpness drop in the edges, pretty much just high end primes. Even my $1300
24-70 is noticeably soft at 100% in the edges. But your typical viewers aren't viewing at 100%, and the only time I ever have anything of interest in the edges is in group shots.
After shooting with my d750 (+ battery grip) for a month, I pulled out my d3200. It feels so TINY omg