Great balance and freedom.
Pros
Great work-life balance. Lots of working from home -- which is especially helpful for new parents or folks dealing with sick loved-ones. IBM shows a lot of trust in its researchers to choose their own problems and drive them. It also encourages collaboration with academia and it's a good way to get interns to come and work for you while staying on the cutting edge and relevant in the broader research community.
Cons
Lots of older IBMers don't get the way the world works today, and that's alarming. The notion that everything open source is winning and everyone wants everything "as a service" is a fairly new concept that hasn't entirely been accepted by all within research. With the research organization being so large there are people who just don't get how to do impactful research anymore. They're so focused on supporting the current busniess that they spend years without any significant publications and lose sight of what are the important problems that will prepare IBM to compete. There's almost a unethical drive to get more patents -- even for stuff we'll never build. In effect, IBM Research is the biggest patent troll there is. Also, the bonuses are *tiny* (around 1% for average performance and <10% for the best of the best performers). I don't know what it used to be like at IBM Research but it's obvious why the best people arrive, love the freedom, and then realize top-notch research will not be rewarded unless it makes it into products within a year. To make up for longer-term results, you have to write patents, since at least that does generate revenue for the division.
