Excellent choice for wireframing of web pages!
Once you get over the default Comic Sans font (which you can change), this is an excellent, quick tool to sketch/prototype the "feel" of a design (as opposed to the look of it in say in Photoshop).
nice design, a lot of UIs and it so easy lo use, I like it
Easy to learn and to use. Very powerful for online prototyping. Solid reusable components and styling. great support and lively community. Possibility for annotations. Weak points - not optimized for printed specification, very slow in collaboration mode