there are many things that were wrong with BP, but the people working there are great and this makes for wonderful environment.
My biggest complaint about BP (while I worked there) was its tendency to centralize decision making. This is different that my earlier experience with Amoco.
For every bad think I could say about BP there would be 3 good things that make the final verdict positive. i have many opportunities to interface with other companies, there are only a handful i would rather work for than BP.