Soy sauce = shoyu = big no-no IMO. That is "wheat sauce" with soy added. And it tastes terrible.
Now, gluten-free non-GMO tamari is a totally different story. Tamari is simply fermented soybeans with water and salt. It tastes very, very different from regular soy sauce, and the difference is stunning. Tamari is so clean, crisp and flavorful while "soy sauce" is murky, salty and flavorless. I never noticed it until I made the switch to tamari, and the taste is out of this world! I STRONGLY recommend SanJ gluten-free non-GMO tamari. IMO, the reduced sodium tastes better, but the regular is great as well. You can pick it up at Genuardi's for around $4. Whole Foods sells it as well, and the regular is only around $3 for the giant bottle and $4.50 for the reduced sodium. It's fantastic and I have the monster bottle on my fridge door as we speak.
Don't put your trust in anyone on this forum, including me. You are the key to your own success.