I've posted about my Vax before, i had a vax rapide previously but upgraded to the V Dual (less than half price from amazon) which i find is a much better.
I find the v duals a brilliant clean on my cream carpets (have dog and toddler and you walk in from outside straight into lounge)
Things i like are... the huge capacity of clean and dirty water tanks, a separate small tank for the shampoo so you don't need to mix it, a wash or rinse option so you can clean with just water to refresh if you want, all pieces come apart so you can clean the machine after use, the brush bar on machine and handheld part rotate and give a great scrubbing action to get into the pile but gently enough not to damage. oh and even when full its not to heavy/awkward to push and filling/emptying is easy and leak free.
It is heavier and bulkier than some, although i'm only little and can manage it fine. The hose attachment is a bit odd but bear with it. It is louder than my rapide was but in a lower/deeper tone (the rapide was shrill and whistly which hurt my ears). I recently used a Crown shampoo (for all machines) from amazon and it was great but much cheaper than Vax own which is also good.
I'd recommend the v dual, but whatever cleaner you get please don't let folk borrow it, as other people don't tend to treat them well (my previous one stopped cleaning and started leaving black marks after a friend used it so i had to replace it).
Carpet cleaners make a huge difference though, my dirty water is often grim but recently i took the vax to a family members and cleaned thier carpet for them - 1st time in 20 years - and the dirty coming out was like tar! even discovered there was a pattern to the carpet :)
Hope that helps