It is ok but really it is a self fulling prophecy. They take a special blend of all the metrics (stock on market, days on market, online search rates etc etc) and create a number out of 100. The higher the number, the hotter the market, which should lead to capital growth (in their theory).
I don't believe it takes into account growth already occurred so it could still lead to a risk of buying at the top. Plenty of Sydney suburbs have very high scores right now, indicating the level of frenzy in the buying market, but ignores the fact that many areas have already had SIGNIFICANT growth.
If you were in the market everyday you would know what the number tells you anyway, and get a good feel for things.
If you are going to trend invest it is one measure worth including in you bag of tricks.
Counter cyclical investors won't use it as we want to be fearful when others are greedy and greedy when others are fearful (Buffet style)