Counterpoint is Hindemith's chief tool. It's not always the standard imitative counterpoint of canon and fugue. Hindemith uses it most often to generate kinetic excitement and interest through cross-rhythms. At its best, Hindemith's counterpoint dances. In the Kyrie, for example, the three upper voices begin in three different rhythms with different thematic material.
Imitation comes into the texture, but the drive behind the music is a lilting triple-time rhythm.
If I were to quibble, I'd ask for sharper diction, crisper consonants, but this seems to me less important than the overall flow of each movement, particularly in the long Gloria and Credo. Gronostay definitely gets you from here to there every time. When you do figure out what they mean, they depress the hell out of you. Life bites and death is the great deliverer from daily suffering. Weinheber's suicide in the 1940s probably didn't surprise too many people.