I used distance learning for three years when I was changing careers. I had to finish the degree in university after passing certain point, which was a pity. Distance learning enabled me to set my own pace and study faster. I recommend it to people who are highly motivated and have previous experience of planning their studies. Books were easier to get and it was much cheaper method than doing the classes locally.
If you have family/partner, discuss your plans and make sure they support you. My husband took three years off to take care of our children when I was studying. I spent several weekends away attending lectures in other part of the country, held a job with 4-hour commute to get experience in new field and did not have much time for anything else than working and writing essays. I had to take computer with me on family holidays to attend seminary discussions. Basically I did 5 years worth of studies in 3. We feel it was worth it, because now I make more money than he does and our family's financial situation has changed drastically.
If you are choosing classes from several universities, make sure they all are counted towards degree. I did this because other university offered cheaper tuition and more web-based classes, and ended up doing too many credits because my old university didn't require as many for bachelor studies.
Make sure you know all the requirements for classes. Also the ones which are not listed in course requirements! I wasn't happy when I was informed after finishing a course that I should have participated in forum discussion early during the week (on Monday or Tuesday, not Wednesday and onwards like I did) and my grade suffered from that. Teacher didn't tell me that during the course, and I was really pissed because I needed great grades to apply for Master's. Our definition of active participation was different.
Work/life balance won't be ideal. Not kidding about that. You can do this, but you have to put most of your hobbies aside for a while. And really take care of yourself, rest and eat well. I was sick most of the time when I was studying and working full time, and actually ended up in hospital for a month after getting endocarditis seemingly out of nowhere. I was 30 and had no previous history of heart problems.