Pros
My department is Grocery, which is essentially the biggest department in the store - all food and drink that isn't fresh. On Fridays and Saturdays there is an extra delivery which has to be worked (put on shelves) during the day, it is quite a hefty amount of stock to do when the store is so busy, around 25-35 roll cages full. Along with doing this which keeps you busy, you have plenty of customer queries to deal with and depending on whether you are multi-skilled or not you sometimes have to answer 'first class service' calls (much to your department managers annoyance) which means lending a hand on the checkouts during busy times. Getting 'multi-skilled' on the checkouts when you don't work on the checkout department is usually something you have to orchestrate yourself, I did it because there tends to be plenty of overtime opportunities on the checkouts as opposed to anywhere else, especially around Xmas. You do sometimes get till trained when you first start, it depends whether you work during busy times or not.
Cons
Any new vacancies in store are always advertised internally before employing new starters, and they have an internal course called 'Options' which trains you for a managers role, all the managers and team leaders at Tesco tend to have worked their way up, so if you are interested in a job at Tesco you are unlikely to be able to get straight into a managers role. This is good because it keeps current staff motivated to work hard, and to be honest if you want to work at Tesco and plan on settling there for a substantial period of time you need to be aiming for promotions. Kissing ass really helps your cause.