XO communications has a very advanced network, and they are constantly looking for new technologies and network trends to improve their standing. The ground force employees are very savvy technically and helpful for the most part, though there is a fair amount of information hoarding in certain areas, and some departments do not want to share. There is a lot of XO pride, and people do what it takes to keep the network running strong.
As with any job, a lot is what you make of it, and XO can be a great place to learn about Telecommunications and networking. If you are capable, and you are in the right place at the right time, you can advance.
The only drawback I saw at XO, was that there was a lot of politics flowing from the top levels down, which culminated in RIF's at least every other year, as upper management pruned and placed their organizations.