Pros
If you put a lot of work and effort in, you will get more hours. There is a good progression system, you just need to be 'seen' as being amazing in the eyes of your management, if you're not then you will have a battle. You can get onto a lot of other tech company benefits, like Apple, Samsung, etc.
Cons
If you apply for an 4, 6, 8 hour per week vacancy, you will be expected to work 39 hours per week, but holiday/base pay will be the contracted hours and not the extra. According to my previous management team it is company policy not to give you full time contracts, even if you become employed in a role that requires you to be on a full-time contract. If you're in this position then contact HR who will immediately deal with the issue, but the problem is management tend to treat you worse than others. Management believe they are above everything and that employees are always to blame, which creates a poisonous atmosphere where many members of staff either go off sick with depression or leave the company. The pay and hours are unbearable. You have to dedicate everything to the job and if you have time off, you'll be expected to come into work (for free) to do things like change your section in the store (for example moving around laptops or general section maintenance). If you are busy doing another job or are merchandising a section and you cannot leave the area as stock not secure, there is a tendency for management or team leaders who are available to get you to serve customers. It is as if the management and team leaders believe their job is not to serve, but to rule.