Pros
Work-Life balance is the best I've seen. The company is fast growing - do your job well and you've got a very stable employment future. The position of CIO is a highly respected role within the company. It's exciting, fast paced and keeps you on your toes with all kinds of technologies. You're responsible for your client's over-all experience with Miles and as such find yourself in ad-hoc management roles with support and project groups on a regular basis ... as such you will definitely keep your leadership and management skills sharp.
Cons
Miles is a quickly growing company with services that are in high demand by it's rapidly expanding client base. Sometimes this means your attention can get pulled in many directions at once, but the company is also really good at recognizing employee thresholds and pivoting, or putting into place new organizational ideas, to keep employee workloads reasonable. You have to be ready for a shifting set of responsibilities to work here ... but if you are flexible you'll be right at home.