Hyper (merriam-webster definition):
2: extremely active
1 : having an extremely nervous or sensitive temperament
If you have an "extremely nervous" Vizsla, that is the product of bad breeding and not the norm. Yes, Vizslas are an extremely active dog, so I guess 1/2 of the definition of hyper is true, but they are not (and should not) be high-strung. Does Riley need a ton of exercise? Of course! Is she out of control all the time? Definitely not. Most people only see her out and about running around like a lunatic... but that is how she exercises. It's difficult to pry her off your lap at home and aside from the occasional cat chase she tends to be pretty laid-back in the house. I guess only V owners know the truth... the V is NOT "hyper", but definitely needs to burn off energy to be a happy pup at home. :)
Now, having said all that, I would not recommend this breed to anyone who is not willing/able to get their butt off the sofa and exercise their dog for 1-2 hours a day minimum.