I totally get that people are not mice, however animals studies have been useful for all sorts of diseases. Are they really uniquely bad for Alzheimer's?

To put it simply, mice don't get Alzheimer's. We're not studying mice with Alzheimer's, we're studying mice with an mutation chosen for resembling Alzheimer's. But we don't know whether this model replicates the actual mechanisms of the disease, or if it's superficial.

No. I believe the problem is with our artificial models of Alzheimer’s in mice.