Do yourself a favor and register for the $5 lifetime membership beforehand. Depending on what time you go, it may save you some waiting time.
https://myaccount.topgolf.com/choose_site
Select the "Riverwalk" location and fill out the information. Type in $0 if you just want the $5 membership when you reach the page for additional add-ons. When everything is completed, you will receive 2 emails. One of which will have a code that they will scan to make your card.
We went on a Saturday night and it took us 2 hours to get a bay. They will text you so keep a close eye on your phone. It would also be a good idea to carpool if you are going at a peak time...although I'm sure this will not be a problem once the novelty has worn off.
Overall it was a fun experience but it would be nice if the entire process was more organized or at least better displayed to avoid confusion. The drinks were meh but I guess that's pretty typical of a sports bar. Its a great place to go if you want a change from Old Town Scottsdale. And, as I mentioned to my single girlfriend, its an awesome place to meet men! ;)