Usability of GI Web applications is already known as an important factor for the acceptance of those applications and their related geodata infrastructure. However, there are still GI Web applications, such as geoportals or Web map sites with many or considerable usability problems. In this paper, we start with a detailed overview of performed usability evaluations and show which kind of usability studies should be used to discover complex usability problems. We perform two expert evaluations, so called usability inspections, based on a Google feature list btw. a typical search user task, as performed in scientific or governmental GI Web applications. We provide a summary of the investigation and performed usability inspections as functionally structured list with typical btw. recurring usability problems, which can be used to avoid these problems when developing new GI Web applications.