There may be too many variables and analysis too subjective to make such a site viable for hotel rooms. On seatguru, things are pretty standard: reduced seat width, no window, no under seat storage, etc. While some people may consider those "negatives" to a particular seat, its really just the "facts" and not opinions that are provided. With a hotel room, something like "very soft duvet" would be subjective. One person's "soft" may be different from another's and, accordingly, a person might book a room looking for the "soft" duvet, only to find out that it isn't the "soft" that they were expecting.

Another challenge would be that, unlike airplane seats, people don't typically reserve specific hotel rooms. Hotels would have to start assigning rooms in advance because, if roomguru took hold, everyone would be looking to book the "best" room. And then, what is a hotel to do when one of their most regarded elites books a room 2 days in advance when only the "crappy" rooms are left.

Don't mean to rain on the parade, just seeing a lot of difficulties with this.