This iron claims to heat up in 15 seconds; it also claims to use some bullshit technology that allows it to "self adjust" temperature according to hair type. Well it got warm but it sure as hell didn't heat up enough to seriously straighten or curl my hair in a mere 15 seconds--in fact, I found that it didn't ever straighten my hair enough to satisfy me.
Against the ghd IV Styler: Although the IV Styler is one of the original products in the ghd range, it’s still pretty beloved amongst customers, especially because of its affordable price. Unlike the new ghd Gold Professional Styler, though, this product only boasts one sensor that stretches across both plates, meaning it’s less intuitive at heating your hair.
For me, the first and still very best of all ceramic stylers [and my dad is a hairdresser too]. It heats up fast, cools down relatively fast, works wonderfully and lasts a long time. In 11 years, I've bought two such stylers. The first one eventually died after 6 years of daily use, rarely skipping a day, while my second one is still going strong. I have no reason to recommend any other styler but this one. My hair is long and very fine.