If I was rejected by UCI as a transfer student, should I appeal it or is it just not worth it?
It depends if you have new and compelling information not originally submitted and you feel UCI made a mistake in regards in evaluating your application. If UCI is a top choice, then I would think if would be worth it.
You have a couple of posts about not meeting your provisional admission requirements for UCR along with missing some Math requirements for UCI. If you are having these issues, I would think an appeal to UCI would not be very successful.