Pros
Not much. The notion of working with the smartest people mostly comes from recent graduates, just entering the field. Same for the cutting edge technologies - these technologies are becoming public domain anyway withing couple of month/year at most since prototyping at company. Besides, work is work, no matter if working with cutting edge or legacy technology - principles are the same. Flexible hours is a big plus though.
Kontras
Middle/lower tier management is a sheer menace. You might provide brilliant solutions/propose ideas/pioneer development in certain areas/deliver excellent presentations - the response would be - ...uh...ok...a-ha... In the end all that stuff you poured your brain on and committed countless extra hours to, would be eventually "rotated" to some other people. If one is self-sufficient enough, he/she would resign to working alone, delivering results and reducing level of communication with superiors (according to workplace hierarchy, that is ) to a necessary minimum. Once in a while, if you're lucky, you may be thrown a meager promotion. In the end this honorable path would lead to elimination from company workforce. When company is doing reasonably well, you are tolerated. Once layoffs are in the agenda - you are out, even with a spotless performance record and track of good reviews.