I've worked at the same company for the past 14 years, I am one of the founders. We do mainly C++ work on Windows and Linux. We're in the financial trading industry. We have grown to about 20 developers.
Every time we hire a new developer I give them a few weeks to get up to speed with someone else and then I meet with them and we talk. I always ask "What do you see that we could be doing better? It could be anything, our process, the tools we use, our structure, anything." And I get literally nothing. I just can't believe it. Am I not asking the right question? Or I'm not asking it the right way? I thought maybe people were intimidated by me so I had someone else do it, HR, team leads, but we get the same result. There are even some pretty obvious flaws that we have like a homegrown, google docs based project tracking system and our lack of using third party libraries but the developers never mention it. And I'm sure there are many other issues that I have trouble seeing.
Prior to starting the company I worked at six different companies and outside of the first one, my first real programming job, I would always have lots of ideas in the first few weeks about how things could be improved. Some of my ideas were bad because I just didn't understand what was going on well enough but I like to think that some of them had merit.
Any ideas how we can get feedback from our new developers on how to improve?
Ask the ones who leave, but wait 5 months until they're comfortably settled into new employment. You can bet they'll give it to you straight, but you might not like that either.