(Different poster here.) I like to call it "Moronix" because their analysis is so shallow, but OTOH they cover topics that no other site cares about, so it's probably a net win as long as you read with a critical eye.
Yes I mostly read it to keep up with some of the Mesa developments, I'd agree that a lot of times they jump the gun and report something as more than it is, or even don't give enough information about some reporting (mostly the benchmarking, but they have gotten a bit better about that lately).
I have always wondered why there has never been a competitor site to Phoronix. My guess is that very few people with the interest and ability to understand things like mesa and llvm are motivated to make a website about it.
What about lwn.net?
They have a tendency to make stuff up. Among other things, they publish performance data which doesn't actually measure what they claim it does.