They are absolutely amazing compared to the books we got from the Tamil Nadu Board way back in the 1970s [BTW, the TNB books -- available for free download -- have also improved, but are not as great as those from NCERT].
Anahita Mukherji and Akshaya Mukul of ToI have a great report on some of the nifty things NCERT has done in its textbooks. Though students' preferences still depend a great deal on how good the teachers are, it's wonderful to see a child react to her text book like this:
... Ankita Kamath, a class VI student, says math is now her favourite subject. She loves studying the elementary shapes in geometry. "The textbook has lots of interesting exercises that we can do ourselves," she says. "We don't need to go for tuitions anymore."
Mukherjee and Mukul do a very good job of telling the NCERT story. Go read all of it.
* * *
FWIW, here's a previous post on how NCERT textbooks handle the issue of reservations.