I've worked for AMD for 12 years, and I've just recently decided to find another job and quit ASAP.
On the whole, AMD is an OK company to work for. But like any large company, you can have good managers and bad managers. If you have a good manager, life is good. If you have a pointy-haired manager, you will be miserable, the same as at any other company.
In the past, when times were good and the company was making money, it was always generous with employees in terms of profit sharing, bonuses, stock options. But of course, the last few years have been the exact opposite, with pay and benefit cuts in 2009. The pay cuts have been restored, and *most* of the benefit cuts have been restored, but there haven't been any merit increases in 3 years.
AMD also has a long history of ramping up the company quickly with a lot of new hires when it's business was good, and then huge layoffs a couple of years later when there's a downturn. The current CEO,Dirk Meyer, has repeated said he's going to break that pattern and put the company on a basis of always being profitable, even in the slumps. So far, his actions have matched his words. What that means is that now (2010) the company is trying to expand rapidly with a lot of new products (Fusion, Bulldozer, ...) but without much increase in the work force. As a result, everyone is overworked, with every department having more stuff it has to do and not enough people to do it.
The working environment is casual, and the new campus in south Austin is nice.
If you work for AMD, you will wind up spending about 1/3 of your time in meetings, most of which are a complete waste of time.