This is probably highly dependent on your team and division, but I felt I had little real world impact, partially because the higher-level strategy kept changing too often.
As I mentioned before, you could work in a private office. It is nice to have your own whiteboard and you can close the door for discussions, etc, but overall, I felt that it was a huge waste of space. The space in my office was used primarily for display little knick-knacks. I would have much rather had the money spent on real estate to go to salary and perks we could have had, such as free food or extensive free snacks and drinks. Also, the offices make MS building seem sterile and outdated. A place of "business" rather than colloboration and innovation, and then, of course, there's also the political bs involved in moving, who gets their choice of which offices, do they have windows, are they close to the bathroom or etc.
MS doesn't have good infrastructure in place for sharing code, ideas, or anything really. Because of MS's disparate businesses, MS can't have a singular vision. That is okay, I guess, but the real problem is how sharing is so antithetical to the culture. They don't allow open discussion within the company. Products are developed in secret. Code bases are rarely shared outside of a division. Engineers have to request access and provide justification to look at code outside of their org.
Yeah, I understand that MS has 100,000 employees and so leaking confidential information anonymously is a real concern. I understand that as a big company, they are targeted for lawsuits and are worried that emails by every employee will be subpeonaed, etc. That said, I think this is a loss for them in the long run. I think what they would gain from being more open and collaboritive internally outweighs the risk of leaks. MS is way too risk averse, even when they think they are being bold.
Too often, on internal discussion lists, I see that when someone posts something critical of some product that they did not personally work on, some one responds with something like, "That's easy for you to say. You didn't put the hard work into it. I'm sure they have important reasons for doing this" etc etc. In other words, criticisms are too often seen as attacks to defend against, rather than failures and feedback to be taken humbly and addressed.
Regarding the Company Store benefit, it is of course, great to be able to buy stuff at a really nice discount. I also enjoyed being able to get MS published games a day early. That said, I do want to point out that Nintendo lets their employees buy games a week early. They also don't put those obnoxious stickers on the box which ruins the packaging. I absolutely hated this. It's like there's some kind of seperation between you and "the Company". Even though you're an employee, you're not to be trusted.