There's nothing more frustrating to a user, in my experience, than logging onto a website or e-commerce platform with poorly executed design. When target pages are difficult to locate, the text overcrowds the images (or vice versa), and the color scheme distracts from the offerings or services on the page, the user frequently decides to leave, even if he/she wants what you had to offer.
Good design should optimize, and then maximize, the user experience. Whether the design is simple or complex is not important; what is critical is that - regardless of the simplicity or complexity of the design chosen - the user interface works smoothly within minimal or no problems. At The Control Group - we test designs in variations, and choose the winning design to implement.
Select images that complement, rather than overwhelm, a page. Use colors that work well with each other, instead of clashing at every cross-section. And most importantly, do not use the Comic Sans font. You have been warned!