Marks is a great company. Their IT department really knows what it is doing, and as a result their in-house inventory and ordering systems work surprisingly well. This makes the non-standard retail part of the job quite easy, and really simplifies the task of surprising the customer and making them happy.
The team at Marks was a joy to work with. For the most part there wasn't too much drama, and they were well organized and good at communicating.
That being said, Mark's is still a retail position, and as such has a host of irritating aspects. Constant standing, occasionally condescending middle management, angry customers and a fair amount of passive aggressive break time scheduling mean that some days could be quite stressful. Also, Christmas music.
Overall, I'd characterize Mark's as the best of the retail jobs. Nearly 0 responsibility outside of showing up and folding clothes, good corporate policymaking, and a great discount. It is boring, but it isn't bad.