Tanya is transformed from someone driven by practicality and valuing human resources in the LN to transferring two of her troops to a position likely to be shelled to kill them off in the anime. This directly conflicts with her original personality. Even the western title is completely inaccurate, opting for "Saga of Tanya the Evil", when her character is supposed to be much more complex.
I need not dwell on how appalling the visuals are in the anime. Many of the side characters are unrecognizable, sporting haircuts that would conflict with military standards and generally look inferior to their manga/LN counterparts (i.e. Lehrgen). The poor designs are not helped at all by the overall ugly art style and copious amounts of jarring 3D models and CG.
