The basic complaint is that GA adds nothing to exterior algebra, which is well understood, even if under-utilized. That the concepts of EA are under-used is not up for debate: Everyone agrees. In fact, by reframing everything from the first introduction to linear algrebra and up in terms of GA, you lose intuition, compatibility, and gain nothing.

https://en.wikipedia.org/wiki/Exterior_algebra

Having read the GA textbook and vector calculus textbook, I can't agree more. The whole thing made me consistently think "Oh cool, so what?". Usually when I read through a grad / undergrad textbook I gain a new way of thinking about problems I want to think about. With GA, it was more of contorting my problems to fit onto GA, and then ... nothing.

However, there were some claims that I did not verify in the GA textbook about being computationally faster and more stable. Those, if borne out, would be valuable.