They are as solid as TUGgers make them. We write 'em. And by writing them and keeping them current, we extend our memberships. So if you travel a lot, your membership can be free.
Along with reviews, members get access to 'sightings and distressed'. Other TUGgers post rare and scarce resorts they come across while looking through various postings. Sometimes these things only last minutes.
Every TUG member will tell you that membership was the best money they ever spent on vacations.