I have both the "official" app, and C:Geo. At version 1.x, the only benefit of the official app was speed. It loaded faster and loaded cache details faster (because C:Geo uses screen scraping and the official app uses a published API). In all other respects C:Geo was superior (ease of use, features, look & feel).
Since the 2.x version of the official app, C:Geo wins hands down because the official app does not work at all. It freezes, force closes, takes ages to start, doesn't shut down (and drains battery).