Pros
I've worked at StorageMart for several years. They are the largest privately owned self storage company and have doubled in size over the last several years, and is continuing to grow. One of the big positives I see working at StorageMart is number of people who start out in a lower position, do great work and get recognized, and are given the opportunity to move up and be promoted. They're a large company, but family still drives a good deal of the business, so I've seen their strong desire to give employees a chance to succeed and grow within the company. I've seen this both at the local level in their main office (in Columbia MO), to their positions out at their stores in the US and Canada. For instance, many of the regional managers working for StorageMart started out as either an assistant or manager at the store. At their main office, some of their top level management started with the company in much smaller positions, from answering calls to managing a self storage facility in the past. If your looking to prove yourself in both your current position, and be given the chance to grow beyond that over time as opportunities arise, this is a great place to work.
Cons
The office temperature can get a bit chilly in the Winter sometimes.