This is definitely one of the best ways to see Cape Town if you're on a very short stay in the beautiful city.
With a few different tour routes, as well as a two day tour option, I'm hard pressed to find a better way for a tourist to get in all the sights. City Sightseeing offers tourists a hop-on, hop-off experience, so that you can check out exactly what you want to see and spend as much time as you want seeing it, while skipping those stops that aren't really of interest to you. I'd recommend doing the two day tour and starting early for both days so that you have enough time to see and do as much as possible.
During my most recent vacation, I got the opportunity to take some friends with me on the City Sightseeing bus and it was honestly one of the BEST days I've ever had! We did High Tea at the Mount Nelson. Stopped to smell the roses at the Kirstenbosch Botanical Gardens. Got a little tipsy from tasting wine at Groot Constantia & took in a magnificent scenic drive on the way back through Hout Bay and along the coastline through Camps Bay & Seapoint.
Check the website for discounts on tickets and tour info