I do it for work - haven't had a need to at home in a long time. I also use VMWare Fusion.
VirtualBox is free (at the moment) and works fairly well, too.
I've only used Parallels sparingly, but it seems to have added advertisements and other annoying notifications recently. You can turn them off, but Parallels is being jerky about how to do it, so users have started spreading the solution in forums and on Twitter.
Parallels take: "We use in-product notifications to share several types of information with our customers. First, and most importantly, we share information about product updates which are generally related to compatibility with OS X, new features and product enhancements. Second, we occasionally share special offers from Parallels or other third party companies who provide special deals for our customers. Many of our customers rely on the information about product updates and appreciate the special deals for products that are of interest to them.
Individual notifications can be turned off by clicking the â€œdonâ€™t show this againâ€ button. However, because customers need to receive important product information, there is not a mechanism for customers to completely disable notifications.
Thank you for sharing your opinion. At times, Parallels staff may remove or edit posts that contain product code information which changes the general nature of the product, as it may affect the overall performance of the software."
Most users take on it: I paid for a product and you are still showing me ads? That's crappy. I agree.