It completely depends on what you mean by effective. If your aim is to improve your overall strength, ability to handle weight, stability under heavy loads then you’ll probably want to look at another type of pressing motion (like sticking with the barbell bench press). If your goal is to put emphasis on the muscle, grow, stay safe etc. then the smith press machine will likely be a good fit for you. I don’t like them because they aren’t very transferrable to the actual barbell bench press.