Pros
Contrary to other reviews, pay is well above the average in the financial industry. However, please don't be swayed by this. Downsides include the 2008 MacBook you'll be paid to struggle with, and the working environment in the Gherkin, which is unpleasant, and often short of toilets.
Cons
Ah, the booming Death Knell of the Death March Project. I can only speak for London, where real talent, and more importantly, real dedication and commitment can be found amongst the troops on the ground. But in the world of company politics, the wrong people have won the war. The technical leadership are a joke, relying on confrontation to sustain them in their misassigned and misaligned roles. How long before these clowns are finally removed is anyone's guess. And delivery management (project management, to you and me) are simply disconnected from the people they need to, er, deliver. As alleged proponents of "Agile" software engineering, these guys can spend literally months "forward planning" - essentially, locked in a room, divining an order to a book of work that makes no logical sense to the engineers building it, and looking distinctly like a series of firmly frozen waterfalls. Fixed contracts don't need to be like this. I have never, ever, worked anywhere with such a high turnover of staff. During my time there, I saw almost 2 entire turnovers of the London engineering team. Seriously, can you find anything else like this on Glassdoor? This is not an environment where you will thrive. Ghastly - avoid at all costs. Save yourself.