if you are a low houred SSP then its a pretty good deal, for such a big company there are bound to be those who love it, and those who don't. I've met both, but by far more of the first group!
For SSP: (not sure on DEP differences if any)
Day 1,
began with a group ex, discussing viability of a route taking into account load figures, profits, competition etc.
we were watched by three assesors.
then the following in any order:
Interview, about an hour.
Computer based tests, 2 hours.
Maths and Verbal reasoning, 1/2 hour.
if you look in the wannabes section of this site, there is a good guide on what to expect in these tests plus useful interview questions.
good luck.
D2K