Pros
Entrepreneurial sprit still exists within Dell - employees who are ambitious and able to seize opportunities can quickly ascend into key decision-maker roles. Relatively few political issues versus other large IT companies I've worked for. Generally a more family friendly, work/life balance friendly environment than I found in my Silicon Valley days. Also, the prevalance of using "meritocracy" as the primary means for salary/reposibility growth seems greater here than at similar orgs.
Cons
Dell is for self-starters - there is no published "playbook" or "owners manual" manual for managing your career. people who are adept at managing their own path and executing without hand-holding tend to do well here. People who want a more formulaic approach to a career path will be frustrated.