Pros
The benefits are awesome. Perhaps a bit on the overgenerous side. You also get to work with a diverse group of operators and engineers, not just diversity in terms of ethnicity, but also in personalities. When business is going well, there is also a lot of Alcoa's capital from a corporate level that the company can tap to make big improvements. Howmet is a relatively recent purchase for Alcoa, so there has been lots of investment in the company. That investment slows down a bit in tough times, but the big projects generally still get approved, more likely if that project is also important at a corporate level.
Cons
Management communication of the important things is pretty weak. Depending on which area you work, you may not get an idea of how the company has been doing month to month. No advance notice when they need to make a workforce reduction. The management heirarchy has been flattened to the point where a promotion often means going from relatively bottom-rung straight to senior management. Difficult to see a path upward through the company if that is your goal. Progression in responsibility is always there, and will likely come whether you were looking for it or not. As a result, it seems like a lot of the people get pushed beyond their limits. Corporate parents means corporation-wide initiatives, so there is the occasional trouble associated with trying to fit a diverse bunch of businesses into the same initiative mold.