Well, according to Mr Clemmensen, it is, or at least, so far, but it's the 31st December today!
Surely he can't go back on his 5-star word. This is his only 5-star review of the year to date, and that means it will land atop his "best-of" selection on the right-hand side of the home page.
And surely Azkaban, by Williams also, will make the top 7 cut? There have been plenty of 4-star reviews alongside HP3, but this is surely one of the few that will stand the test of time, and it certainly has consistent fan-base approval, perhaps moreso than his top-7 achiever HP1?