The salary isn't great, but they are transparent about this, so you'll know how much to expect in your first year and second year. You should see this as a place to get experience and a foot in the door of a big company, not loads of money.
Having said that, you don't get paid (or become an employee) until you start your client placement. This means you don't get paid during your training, or any time between finishing your training and starting your placement. At the time I finished my training there were limited client placements available so I was sat in the academy for an extra 2 months doing nothing on £0 pay, when I had been given the impression I would be placed straight away after finishing my training. I wasn't at all financially prepared for this extra 2 months without income and really struggled to get by. If you have 6 months savings to support you through training and the potential wait until placement, you should be fine.
Major downside is having to be UK geographically flexible, so if a client wants you after interviewing you, you have to go. The job and location are pretty much pot luck. The location I went to was nice and the client was great, but I realised within the first month I really didn't enjoy the job at all and had to stick at it for 2 years. I stayed with the client after my 2 years because they were good to work for and I needed the money.
