I have a finance background and previously worked for UBS and in retail and wholesale stockbroking. I fully understand the role of, say, market makers in the financial system (ie providing liquidity).
I hear those same arguments being used for HFT but honestly they don't really stack up (IMHO). I don't really see HFT doing anything harmful however so ultimately I don't really care. I can see the appeal from a technical background of being a quant. It must be a challenge and I'm sure you can make a lot of money, which is fine, but it doesn't really contribute anything to the financial system.
The real problem I have with Goldman (and their ilk) is the serious crises they've instigated all the while banging the drum of contributing to the financial system.
This includes the subprime crisis [1] [2]. Goldman wasn't as guilty as some but its hands weren't clean either. You'll often see the "don't hate the player, hate the game" defense here. Sorry, no sale. You're accountable for your actions regardless of the incentives.
More disturbing is that Goldman (and their ilk) is killing people in the name of profit [3] [4]. Sorry, but that's morally reprehensible no matter how you look at it.
Now US regulators have made at least five mistakes (IMHO) when it comes to financial regulation:
1. 30+ years ago allowing investment banks, once partnerships with unlimited liability, to incorporate and have limited liability for their actions;
2. Not allowing investment banks to fail ("too big to fail" like Merrill Lynch). Bailouts of investment banks could reasonably be described as welfare for investment bankers;
3. Allowing banks to take positions as well as operate as market makers. There really should be strict separation here;
4. The carried interest tax treatment of hedge funds that mean executives pay less tax (as a percentage) than most of the population. Congress really has been bought and paid for here, most notably Sen. Chuck Schumer (D-NY) who has steadfastly broken with party ranks to resist carried interest reform [5]; and
5. Strict regulation on commodities market to separate speculators from hedgers. Driving up food prices causing untold misery even death should result in criminal liability for the organization and key personnel.
So work for Google. Don't work for Google. Whatever floats your boat. Ultimately (IMHO) I think Google has a net positive effect on the world.
Whatever you do, as an engineer, I strongly believe you should stay away from investment banks and hedge funds as you're actively contributing to misery in the world at this point.
[1]: http://dealbook.nytimes.com/2013/08/12/in-one-bundle-of-mort...
[2]: http://money.cnn.com/2010/04/24/news/companies/Goldman_Senat...
[3]: http://www.theguardian.com/commentisfree/2013/may/23/goldman...
[4]: http://www.fool.com/investing/general/2013/07/23/how-big-ban...
[5]: http://www.nytimes.com/2007/07/30/washington/30schumer.html?...