Pros
Not only is Caterpillar the global leader in what it does, it is refreshingly committed to sustainable development, high value (not just low cost) manufacturing, and excellence. Caterpillar has a core of values called Our Values in Action, that stress Excellence, Team Work, Integrity, and Commitment, and I truly sense that these values matter. It is fulfilling to be part of a "team" that commands its market, exports globally from a US-centered manufacturing base (how many companies can still say that?), and embraces good corporate citizenship. There are excellent opportunities for overseas assignments and travel, a wide range of competencies, a relaxed atmosphere (not true at all locations, of course), and reasonably generous overall compensation (including a performance-based lump sum annual bonus that increases as a % of your salary as you progress up the career ladder). From my experience, it is also family friendly. Managers are allowed to work from home if need be (sick child), though off-site work isn't common, and there are subsidized family activities. Peoria is a very cost-effective place to raise a family, and Caterpillar's salary and benefit package are easily the most generous in the metropolitan area (and go quite far).
Cons
Can be very bureaucratic. Similarly, it is hard to institute change with many people having a vested interest in the status quo, and simply hoping to ride out their careers to retirement with no shocks. This is probably true of many large corporations, of course. Peoria and some other Caterpillar locations may not be attractive to young, unmarried, more "cosmopolitan" workers, but hey, it's a heavy equipment manufacturer, not a software development firm.