Pros: Ions! Built in diffuser style (if that's what you want)
Cons: Not for those who don't want a diffuser-only style
I bought a Vidal Sassoon Ionic Diffuser Dryer at Target a month ago because my old hair dryer finally pooped out and stopped working. I use a hair dryer almost every day so I had to get something decent, and quickly. I saw all these "ion" hair dryers that I had never seen before, they seem to be a new thing (?)... they are all a little more expensive than the "regular" hair dryers but I was intrigued by the claims that ions would help dry your hair faster and smoother. I also like to have a diffuser, but the diffuser attachment on my old hair dryer just kept falling off all the time, so this Vidal Sassoon built-in diffuser style hair dryer caught my attention.
This hair dryer does seem to deliver as promised! I noticed right away that my hair was smoother, with less static. This could also possibly be due to or helped by the fact that I started using the new Garnier "Fructis" shampoo and conditioner around the same time as I got the hair dryer... (also recommended, by the way!). My hair has always been so straight, and usually quite limp along with that. But now it seems much more manageable and soft (when I use the hair dryer). I also apply ThermaSilk mousse prior to using the hair dryer, but this is something I've always done, so it alone wouldn't explain the change (but maybe it "works" well with the ions?).
The dryer does seem to dry your hair pretty fast, faster than you would expect if you judged only by the heat/velocity of air coming out of it. I don't really use the "cold shot" feature, but this is another feature on this hair dryer if that's something you're looking for. Since I've only had it a month, I don't know what the expected lifetime or durability might be - but I've dropped or banged it a few times already and it's been fine so far.
Here is Vidal Sassoon's appliance store, where you can read a little more about this hair dryer if you'd like: