okay - let's get this out the way first - bonuses. Unless you're one of a lucky few, don't start thinking of mansions, fast cars and so on - it's media hype. Those days are gone for most. Numeration day is a total joke (almost insulting) so unless you're pulling in hundreds of millions for your boss (unlikely) don't think you're on the ticket to success when you get here. Learn lots, work hard and see what happens - but it's not Leonardo DiCaprio wolf of wall street ticket to success stuff. You missed the boat big time on that one.
Crazy working hours. Yes, you get paid well however when you work it out per hour it becomes very average. If you're contract says 9-5 don't honestly expect to work those. I work 8:30am til 6:30pm (middle office) - a lot of my team work longer and we aren't compensated like successful traders / sales people (most old school are long gone).
It's the same everywhere I've been, especially in banks - politics. It's a huge company and people are looking after themselves - it doesn't mean you're going to have a terrible time but managers are so busy looking up pandering to the needs of those above and playing politics with others that what chance to those at the bottom get? Real leadership inspires, nurtures, listens, etc - but most in leadership roles (big and small) are not natural leaders.
With the greatest respect to those in India; stop offshoring Barclays. Seriously, I know you can get 3 Indians or more for the price of 1 in the UK or US but it's about value and not price for what you get. Let's not confuse value and price. Half the company is based out in India by workers utterly confused and inexperienced, not able to think beyond their checklists printed for them. Empty promises, not delivering work, when it is delivered it's all wrong or fudged - ah, I can go on. Seriously, it's easier to get up and work with one person on the other side of the floor.
Some teams can be a bit 'old boys network' but they are rare. It could be much worse - most are normal.
The biggest issue at Barclays investment right now (early 2015) is that it is run by a chap that knows retail banking (CEO Anthony Jenkins). The investment bank is a mere child compared to what it was a few years ago and staff morale is low. It's low because people are heavily overworked due to ruthless job slashing yet the business keeps demanding more and more - there is no more juice to squeeze. I get the feeling the top guys want to turn the overall Barclays group into a retail bank and sell of the investment part eventually - so long as it's providing a good enough return then they'll keep hold. But seriously, the workforce are drained, exhausted and good people leave within just a year.
The bank has tens of thousands of staff. Even those extremely good at the bottom deserving promotion have odds heavily stacked against them because of the numbers game. It's very hard to get noticed when you have so many also wanting to be noticed and seen as 'special'. Don't expect quick promotions, like with most banks (a lot of good timing and luck involved) rather than natural talent and skill.