I have wavy hair but also like to dry it straight sometimes too so I have used it with the diffuser and without. I have very thick hair so it takes forever to dry. I can't believe how powerful this hair dryer is! It literally is the strongest hair dryer I've ever had! I love it! It took maybe 5 minutes to dry my hair instead of over 10, like usual. That was amazing! Love being able to save time and even though it dried fast it wasn't frizzy when I diffused it. I got this hair dryer for free but I would definitely pay for it!