Okay, again, this comes from the view of my last few months at the firm:
Advancement- If you want to advance beyond your current role (or beyond that), you should have joined 3+ years ago. They are going to hire middle and top management from outside the company (probably old friends of the executives) and that's just how things are going to be. Period. It's not that those outside hires are going to necessarily be bad, some are, some aren't, but those roles are not going to you. You will work until you realize the gig they are playing, then you will leave, write a Glassdoor review, and then get replaced by the next guy/gal and the cycle will continue.
Compensation- I left for a job with fewer hours and more than twice the pay. This is in no way an exaggeration. Now, to be fair, my experience with those stats is not at all the norm. But given my time and impact to the firm, it highlights just how intense of an effect year after year of small incremental raises can have on your salary. I was working so hard and for so long, I simply didn't realize how much the skills I built would go for in the market until I searched. Pease don't be the next person here or anywhere else to stay too long.
Sentiment- the two above things create one big issue, discontent. As a poorly formed analogy, working for ADC is like Dorthy going into Oz: First you just get your bearings figuring out where you are (like any company), then you meet some great people who all want to work together and reach a common goal, but then you realize this place is not what you thought it was and you want to get out. This manifests itself in lots of young employees who are hard working and supper happy with the culture and lots of older employees (2+ years, so not actually old) disgruntled but holding on hope that "soon things will be better here."