I volunteer personal train here for the swim portion of triathlons. The pool is a nice size, staff is friendly, lots of classes, and there is a lot of equipment. For the price it really can't be beat.
Very difficult to secure a volunteer spot (over a month to get it and had some friends turned away...)
Like a lot of cool things, the Y tries to be exclusive by hiding itself in the Thunderbird business campus so be warned so you don't call sounding ridiculous claiming that it doesn't exist like I did ;)