Pros
The 401k in the USA is pretty good. You should get a return above 6% of thereabouts. No reason you won't have over $100k in your 401k account after 5 years. This is the only pro to working at this company.
Cons
If you're looking for a technology position, I would go to a technology company. Fidelity is a financial services company first, and as a result they have some questionable practices. They have their own version of agile which just doesn't work. Be prepared for hour long stand ups in the morning, project managers that are not technical and fail to keep track of meeting minutes. From a salary perspective Fidelity is way behind technology companies. I left a senior position in Fidelity, and joined a junior position in a technology company. My salary went from $74,800 to $120,000. Once you get to senior in Fidelity, the path to principal, manager, director and above is almost non-existant these days. Your promotion path is not based on job performance, it is based on putting the time in with the group you're with. This much was admitted to me in my review meetings. If you join as a senior or get promoted to senior and want to be promoted to principal be prepared to put in more than 5 years before even being considered for it, and chances are the company will use a down turn in the economy as a reason for not giving you the promotion you deserve. If you're near retirement you'll be fired so the company can save money by not giving you a full retirement package. I know a lot of people that this happened to in 2008, and again recently. The company keeps changing direction. When I joined in 2007 teams were organized by function - developers, testers, etc. Recently they re-organized by product. You can be sure in another 6 - 8 years they'll go back to being organized by function after an independent consultant comes in and makes the case for it. Every 8 years the company sheds around 10 - 25% of their staff - most of them are the people it pays the most.