rating of how the mesh looks 2/10, rating of how it looks for your experience 7/10.
i'll take a stab in the dark and say you're box modeling the guy, and only modeling one side then mirroring it, correct?
well, the reason for that large seam down the middle is that it also seems you're applying mesh smooth, however for thsi to work you need to weld/combine all verts staright down the center. otherwise what you will get is mesh smooth applying it only to what it considers seperate models even if they're attached. but if the two attached models share the same verts along the center you'll get a nice clean mesh smooth with no seam down the middle.
for more info, refer to
this topic here for good advic when modeling a human.
however, if you're not mirroring then get rid of that large crease in the middle, it is not needed.
-------------------------Only a fool claims himself an expert