First and foremost keep in mind that mice need a lot of care and attention. So don't get one without learning proper care or thinking its as easy as changing its papers.
Teensie came into my life on pure accident. I had worked with many mice and rats through a rescue, but had never owned one before. On an outing to PetSmart for supplies for our rescue fosters, I stopped and looked at the mice cages. My husband wanted to look at a little black one with a white mark on his head. So as I reached in to get him for my husband the black one went to bite me. Teensie flew into action and saved my hand from a nasty bite. She crawled into my palm and out she came. I fell in love instantly with how teddy bear her appearance was and she was so calm. Seeming to just want to sit on me. I purchased her and all she needed and home she came.
Teensie was never a cage type she enjoyed riding along on me or my son everywhere and would sit and stay if instructed to do so. I read books and scoured the web on training topics for mice and worked with her every day. She was quick to learn and eager to please. Overall having this tiny mouse proved to be one of the most enjoyable experiences I have ever had with an animal. Sadly my sweet little mouse passed away from cold. Our home was broken into and the thief left the window near her cage wide open in winter when there was a freeze. I have never cried so much over the loss of any animal.
Mice take work but are intelligent animals who learn quickly if the time and effort is put into it. You have to make sure they have an environment that provides lots of exercise for them as well a a proper climate for them to survive. They have very low life expectancy as well so if you get overly attached easily. I would avoid them unless you want to cry for a long time when their time comes. But if you can handle that shortness go for it. Because you may be surprised how much such a tiny creature can improve your life. I know Teensie did just that for me.