As background to answering this question, I've worked in IT for banks for nearly 30 years. My experience spans the whole range, including design, development, QA, project manager, IT manager, and so on. This is London-specific, but most of it also applies to Wall Street.
Banks in the City (London's equivalent of Wall Street) do tend to pay well for developers, mainly because they can and because they want to attract good developers. In general, the closer you are to the front-office (trading/sales) revenue stream, the better the pay. For developers, this ranges from £30K ($44K) to £200K ($300K), excluding bonus. The bonus is usually around 10-30%, but can range as high as 50% or even more for good/senior people.
Like any industry, some of the work is very interesting, some is horrible. The technology stack tends to be at least one generation behind current. Domain experience is highly prized, and can be lucrative. In most banks, there are multiple opportunities to add value and make a difference. The industry tends to favour and reward go-getters. And once you start really climbing the greasy pole, the money can be very good - £200K ($300K) basic + anything up to the same in bonus. NB This is for senior IT managers, not developers.
The hours can be long, depending on the bank. You might be able to work 40 hours at some banks, but you probably won't go anywhere. 45-50 hours is the average, and 50-60 hours as you earn more money or if you're ambitious.
You often need to learn about specific products and business flows in order to add value. This can be boring for some people. You may end up supporting one or more legacy systems, but you soon learn to spot and avoid this trap.
Working conditions are far from ideal. Noisy, constant interruptions, and so on. Many of your managers will not have good people skills.
If you're a developer who loves his craft and hates the idea of stepping out of his comfort zone, banking IT probably isn't for you.
If you're happy to be top 20% in 3 or 4 skills (rather than top 5% in one skill), and if you really want the money, then try banking.