I use Suffusion on my personal site, and business sites - whenever I can convice someone that buying a pretty (but custom) theme and then manually changing code and CSS isn't a good idea. I realize many people don't want choices, and for them a paid theme or a simple theme that does most of what they wanted is a lot less work. But - if you then make direct, coded changes to a theme you purchased (or a free theme for that matter) and make it harder to maintain, you might want to think about using Suffusion instead.
Yes, there is a learning curve. But, working through all the options taught me a lot more about what is possible with WordPress. If you want options, Suffusion has them and has them organized in a way that produces a level of flexibility I could only imagine matching with direct changes to CSS and parts of WordPress. I don't want the maintenance headaches that causes. I use Suffusion.