Vantaggi
Some really nice people are working there, especially at a junior level. The juniors get on very well, and meet after work. Non-Spanish people come from top UK universities. As for a consultancy hours are very good (many juniors leave at around 6-7pm), however occasionally you would get on a project that requires you work very late hours (mainly for the face time rather than for actual workload).
Svantaggi
They do not manage their workforce effectively - junior people are without any or little work most of the time. Projects are very very dull, very little strategy work, and in the UK they work pretty much with one client, so there is very little variety in work (and risk for the company's future). Very unprofessional - you get a lot of lies in the recruitment process, seniors don't always act and talk professionally around clients, and there are some weird practices in place (e.g. a manager can perfectly ask you to stalk a client around the office...), HR people avoid putting things black on white and you can never prove that they have promised/told you anything. The salary is not competitive to what is offered in other consultancies. I only recommend to join them if you are terribly desperate for work.