Make of this what you want. If you are in Guwahati it is likely you will want to visit the temple on this island which is well worth a visit. But do it for the boat ride, which is scenic, and not for the actual island or temple which are, quite frankly, simply not that special. The island is small and all that is there is temple itself (there's some mention of golden langurs but we didn't see them); and the temple itself is small and not particularly attractive.
If you own or manage Uma Nanda Temple, register now for free tools to enhance your listing, attract new reviews, and respond to reviewers.