I can describe a book as "a good read." But can I describe a number of books as "good reads?"
Your question has nothing to do with grammar: good reads is perfectly grammatical.
The question is whether it is idiomatic. I'm genuinely unsure of this. I think I would be more likely to say They're all a good read, with a distributive sense. But I would not find it odd if somebody else said They're all good reads.
[Side note unconnected with your question: I am guessing that you are not a native English speaker, so I want to point out an oddity of English which often misleads people. Few books and A few books denote the same thing - a small number of books - but pragmatically are very different. If you say few without a, you are emphasising how small the number is. So idiomatically few books means something like not as many books as you might have thought; as opposed to a few books which is neutrally a small number of books. Apologies if you knew this, and it was just a typo.]
goodreads.com certainly thinks so.
Sure, read is a countable noun. If "something that is read" is a read, then several somethings that are read are reads.
[Edit: Note that the American Heritage dictionary flags this usage as informal, while other dictionaries find it unexceptional.]