The Gass Forest Museum is an old-fashioned natural-history and forestry museum, the kind of place where cabinets, specimens, timber samples, and taxidermy still do much of the explaining. That suits Coimbatore, a city close to the Western Ghats and long tied to agriculture, forests, and industry.
It is not a slick interactive museum, but it has character and useful context before trips toward the Nilgiris, Anamalai, or other hill-country landscapes. Go for the collections and the institutional atmosphere rather than expecting a polished contemporary attraction.