I go to Shaaz mainly for hair cuts, so I'll limit my review to that.
I've been getting my hair cut at Shaaz for almost 10 years now after having tried other significantly pricier salons in the area. Sharon, the owner, is simply amazing with all types of hair and over the years I've converted my friends (both male and female, of all different ethnicities) over to Shaaz.
Aside from regular hair services Sharon has a real talent for up-dos for special occasions - in fact she did my hair and the hair of all of my bridesmaids for my wedding.
Seems to me that all of the negative reviews seem to be from people who bought vouchers from deal sites and who think it's acceptable to tip based on the voucher value (typically a small fraction of the actual cost of the service) rather than the value of the services rendered. Note to you people: if it's not already obvious to you as common courtesy, almost all of the deal sites indicate you should be tipping on the pre-discounted amount. Stop being so cheap and rude.
I can assure you that I've never once encountered any of this supposed "mandatory tipping". But then I pay full price for my hair cuts at Shaaz because I think they are worth every penny for the friendly, attentive service I get from Sharon.