I have REALLY difficult hair - fine, knots without me doing anything, frizzes like I'm plugged in and curly in a horrible Krystal Tips fashion. Babyliss products do nothing but damage it and I have problems using one of my arms, which also doesn't help.
Currently using a tiny Ego travel dryer as it's light, quite fast and doesn't make my hair any worse than it is. I have used my niece's Dyson several times and my friend's a few times and love it. It's light and balanced, making it as easy to use as my tiny Ego. It's really fast, again helping with the (awkward for me) process. It doesn't dry or fry my hair (unlike every Babyliss dryer/brush/straightener I've ever used), so I can see a massive difference in the texture after using it.
My niece has very thick, wavy hair that used to take an hour to dry. She can now dry her her straight in 20 minutes. My friend has lots of fine, straight hair and isn't that impressed, apart from with the speed - but she has the kind of hair that is easy to handle and doesn't take long to dry to start with.
I'd say that if you don't have any issues with your current dryer or are lucky enough to have manageable hair, don't bother. But if you have difficult or very thick hair, it would work well enough to notice a big difference. Time is money - if you spend ages drying your hair why wouldn't you upgrade to something that will save it. But look for a good deal. I'm waiting for a 10% off/triple points combi at Boots! My niece had hers like this so the price came down quite a bit.
I've been wondering for ages why I've never seen the L'Oreal Steampod on one of these shows. Now, this is one thing I will NEVER be without. I even have a small saving fund in case mine breaks (though it's a good few years old now and still going strong, I only ever use distilled water in it, despite living in a soft water area). The only thing I have a gripe with is the size for travelling, but I bought a smaller version from Amazon that has an on-board little water tank for that. Steampod sorts my hair in minutes. My mobile hairdresser is always amazed at the difference between her GHDs and my SP when she uses it. Plus my style stays put, even if I get caught in a bit of drizzle. GHDs aren't a patch on it for straightening and they damaged my hair. SP gives my swishy, silky, shiny hair - which after having fluffy, frizzy curls-horribly-at-first-sign-of damp hair for the first 40 years of my life is absolute bliss.