Ventajas
If you're lucky you'll get interesting clients, with interesting work in good, central locations. If you're HQ based you'll get free pizza every month, and work in a nice modern office with the option to have a massage every month.
Desventajas
More likely you'll be sent somewhere with a ridiculous commute, because the scheduling team are based in Cape Town and couldn't care less about your work\life balance. You'll also miss out all the perks because you're on client sites all the time anyway - that isn't a moan, just don't be taken in by the promise of these things because you'll never be about to take advantage. You'll probably be doing work which doesn't match your skillset and you'll be bored silly. You won't learn anything. Holidays need to be booked at least a month in advance, no matter what reason you need it for, and even then they'll be rejected last minute. To be really sure you need to book them even further in advance - sucks if you need a doctors appointment or need time for personal reasons.