The S3 has been the most bug-free Android device I've ever owned (and I've owned a lot
). In fact, it's had less random reboots than the iPhone 4S I had over a period of several months.
As with any device, you'll see people posting about problems they're having. There are going to be issues that people will experience with every phone out there. Plus, it's often tough to use forums as a gauge for major problems with a device. A lot of people only post when they're having problems, so that's why you'll see a lot of threads - for every phone on the site - about issues. Most people don't post a new thread just to say "I love this phone!"
One of the best ways to use a forum to judge a device's potential problems is to see who is posting about the problems. Are the post being made and/or confirmed by long time forum members who are active members of the site, or are they made by people who tend to post only when they have issues? If posts are made and confirmed from long time members who are active in the Android community, then there might be some cause for concern. But that hasn't been the case with the S3. That's not to marginalize the problems had by those who aren't very active on the site or who are new, because they are indeed having issues. And that's part of the reason why this forum exists - to help people who are having difficulties with their device. But as you mentioned, many of the questions are related to operator error or a lack of knowledge about their device (and even long time members have a lack of knowledge about many devices). So, look at who is asking the questions and if answers are being provided.
The biggest complaint seems to be weaker reception, which is common among Samsung devices. While the S3 isn't quite as strong on the reception front as Motorola devices I've owned, it's definitely the best Samsung device I've had, and it's on par with most HTC devices I've owned. I haven't run into any signal issues myself.
So, all of that said, in my experience the S3 has been phenomenal. I haven't had a single issue.
