Incorrect.
negative Mean curvature values: then that part of the surface is bowl-like - convex (viewed from the side of the surface normal) or saddle like with one principal curvature positive and one principle curvature negative.
positive Mean curvature values: then that part of the surface is saddle-like - concave (viewed from the side of the surface normal) or saddle like with one principal curvature positive and one principle curvature negative.
zero Mean curvature value: then that part of the surface is flat in both directions or a minimum surface with the principle curvatures equal in magnitude but opposite in sign
Is there a reason you want to use mean curvature rather than Guassian curvature to analyze whether the shape is concave, convex or saddle-like?
Edited: concave and convex corrected.