It's a very nice website for sure, and a valuable tool, yet it doesnt seem inclusive. I found no mention of certain pieces, and the criticisms... I had to view them with a grain of salt, especially when compared with transcriptions which the compiler didn't include for whatever reason.
I chose to look past the subjective criticism, which is obviously a huge part of classical guitar study, and I believe this is important when studying guitar; to find ones own voice in the notes, rather than imitating what others play.
And also a grading system is irrelevant to me. Play guitar well and make beautiful music, regardless of difficulty.
But it certainly is a great value in referencing and comparing different versions of pieces, even when they aren't all included.
"Pay no attention to what the critics say. A statue has never been erected in honor of a critic." -Jean Sibelius