There are numerous composting bin options available these days that create compost at various speeds and quantities. The benefit of having a grounded compost bin is that earthworms and microbes from the soil come up into your compost system. These assist in the decomposition process.
One of the benefits of a raised compost bin is that they are more of a deterrent for rodents. Animals are difficult to deter in either situation but rodents would definitely be more deterred by a tumbler than a grounded bin that they can burrow up into.