Couple o thoughts,
Flight instructers teach you how to set up a plane so it will fly right. That likely is a major contributor to success. Trouble shooting a new plane for a new guy is near impossible or at the least agrivating.
Also there is a very large assortment of electric trainers these days. I have instructed on some recently and have been impressed.
others not so much. easy to fix is a factor for me as well.

The GWS slow stick is a nice enough plane to learn on IF THE WIND ALLOWS. I would look for something a bit bigger such as the Apprentice. But I usually tell new guys NOT TO BUY A PLANE until they have an instructer. Having a trainer the instructer is familiar with just makes sense. Our club often has a trainer around a serious student can have.