I worked in the hair industry for a while so I've used a lot of high end flat irons and I got to say, this one did not impress me at all. I'd never used a GHD before this btw (none of the stylists I know have one) but I ended up ordering the GHD classic styler--which btw seems to be the same as the "IV styler"--instead of the CHI Turbo due to the fact that at the time, the GHD was on sale and basically the same price yet it offered more versatility (the turbo has a velvet cover so you can't use it to curl).
To have straight hair, you just mist your hair with the GHD thermal protector. You then start at the part of the hair that’s closest to the roots, and then you glide the GHD Classic 1-inch Styler to the tips in one smooth stroke. You can also follow the easy directions for soft movement and for curls, which involve some turning while you glide from root to end.
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.