I haven't been on Engadget's site for a year or two, but when I did go there, they didn't have the time of day for anything but the iPhone. Apparently that's changed because before there wasn't an iPhone that got below a 9 rating, and there wasn't an Android phone that got a 9 rating (going by their rating scale).
Regardless, all of these sites have their own biases, no matter how impartial they try to be. The reason being is the reporting is done by humans, and we have a tendency to be biased now matter how hard we try. Doesn't matter if the site is OS specific or covers everything, sometimes it's the entire staff, sometimes each writer has their own bias apart from each other. And it isn't limited to the mobile industry, look at Consumer Reports. It's a safe bet that domestic cars will do poorly, and foreign cars will excel.
What I do is find review sites that have rated stuff I already have, and see if they come to the same conclusions as I do. That way I know that I'll probably have the same experience. It's really the only way make accurate use of their reviews, it should be in line with what you want, not what everyone else thinks, because you're going to be the one dealing with it.