Balsamiq has helped democratize interface design in the communities who use it. A broad range of people coming from different roles and fields have adopted sketch-style wireframing. Making ideas come to life quickly with wireframes is a revelation. Your newfound power to create user interfaces is exhilarating!
Soon enough though, beginning User Experience Designers realize that creating products that are easy to use is actually quite hard! You have to know about information architecture, interaction design, copywriting, and lots more.