One of the biggest issues is that it's very hard to progress up the ranks there, especially once you get to a manager level (e.g. sr. manager, group manager). I finally left because of that. Making a jump to Director + levels moves at a glacial pace (even though there was a huge initiative to promote from within when I was there). Intuit prides itself on being particular about people, but I think it ends up doing itself a disservice because great people want to move up through the ranks; if there is no where to go (or no role model of others being promoted), it gets to be discouraging quickly; no one wants to be a Group Manager for 5+ years.
While Intuit has an excellent performance management framework -- the best I've seen in Silicon Valley -- ratings and management are inconsistent across the organization. For instance, some teams would be great at weeding out the dead wood; in others, they'd hide out next to the copy machine for years. The company is packed with lifers, which can sometimes be the sign of a good place to work and sometimes the sign of lazy management. For Intuit it's a little of both. I had to fire 2 people in the first 6 months I was there, mostly because they just got passed around by lazy managers.
The business itself is at an inflection point. It's really riding on Tax at this point; that is a legitimate, healthy web business. But every other part of the organization is struggling with how to incorporate the web and stop being a moribund software giant. And that's a tough challenge. Intuit can't skate by on Tax forever; there are lots of other competitors (called "ankle biters," which I loved) that do as good or better and are significantly cheaper. Quicken in particular is on total life support. Brad Smith really has to find some new, compelling business models.