Career advancement - While there are a lot of great learning opportunities in the early stages of an IT career, your prospects dry up fast after about 3 years. GM IT has a horrible habit of burning out top talent - if you establish yourself as a dedicated, talented employee, you are more likely to get stuck with the same work over and over again until you are hating life, rather than interesting, high visibility projects to advance your career because your manager only cares about the bottom line. If you think you can just switch teams think again - constant political battles between middle management make it very difficult to change to a job you'd rather do. And even if you do make the switch, you'll likely mess up your chances for a promotion or have to take a pay cut because HR has way too much control over employee compensation and makes it really hard to get a pay raise. They (HR) recently established quotas for the number of people in each organization that can be at a certain pay/benefit grade, and most teams are over the line so 90% of employees are stuck at their current level, by default. I've seen a lot of people quit recently because they were approved for promotions (sometimes by directors and/or executives) but were denied by HR (a lot of them were women, what's up with that Mary Barra?) who cite "policy".
Perks - Although GM's traditional benefits are very good, a lot of the perks you'd expect to see with a huge car company are just not there. You don't get a company car unless you are a senior manager or higher, and even then you'll likely get stuck with something clunky that GM can't sell. Only the executives get the "cool" cars. There used to be an awesome program where more junior employees could try out cars for a week, but the company took it away to cut costs. This really sucks because employee discounts on GM cars are embarrasingly bad - most people use standard retail discounts because they are actually better.
Culture - GM recruiters sell the IT department as a "tech startup funded by a multi-billion dollar corporation". In reality, it's more like a "large consulting firm under long term contract with GM" in that there's very little of the aggressive,
innovative culture that you would see in a startup. Red tape is everywhere - you need 3 to 5 approvals just to get read-only access to a non-secret production database for example. The more established you get, the more time you'll
spend in endless meetings, which usually results in worse work-life balance because you end up doing most of your real work after hours. The rest of GM hasn't really embraced IT either...you'll spend about as much time selling your work as you do actually doing it.
Middle Management - Middle management and tech leads are, by and large, awful. There's a few exceptions but most of them are petty, lazy, and constantly playing politics. Many of the ones in Austin have been working together for 20+ years, so there's a lot of nepotism and playing favorites. A lot of the reason for the career advancement logjam that I mentioned before is because some of the managers brought in "paid friends" from other companies at job grades way higher than they deserve, so they are enjoying high pay and company cars for very little output and preventing other people from getting promoted. If you aren't part of that culture and don't pay homage to the old boys club, forget about gaining any sort of career clout. Many of them have a consulting mindset and tend to overpromise to the business, signing up their developers for work they either don't know how to do or don't have time for (or both), and which usually doesn't deliver much value or isn't functional, but "it's what the business wants and we have to do as we are told...so...¯\_(ツ)_/¯". Many of them also get road rage in the parking lot and on commutes - we are constantly going over safety messages because the company cars are always getting wrecked or getting tickets for bad driving.
Infrastructure - GM's IT architecture is ancient, cheap, and something is almost always broken. This can make it really hard to test and deploy code because you'll often have to wait until environments are less busy or fixed in order to do your work. The old Austin IT facility was a former Dell building and was a great work environment. Lots of natural light, bright colors, and open air. The company is moving Austin IT to a new building, and it feels like a massive downgrade. It's an old warehouse which is very obvious. Exposed piping/wiring everywhere, exposed insulation on the ceilings which periodically falls on you, very few windows, drab and grey walls and floors, HOLES IN THE FLOOR UNDER THE CARPET and generally not ergonomic or safe. All the "renovations" feel very rushed and cheaply done. Even basic things like bathroom plumbing and water fountains barely work.