From what I read--Advantages for the front loader: easier on clothes so they last longer, uses significantly less water, quieter. Wouldn't it be nice never to have to make the mad dash to deal with the wham-wham-wham of an out-of-balance spinning toploader? The larger machines in the laundromats are all front-load; have you ever had to open one to redistribute clothes in the spin cycle?
Disadvantages--more expensive up front, smaller capacity, longer cycle.
I know a few people who've switched to the front loader, and none would switch back.
I'd do it myself if I were in the market, no question.
Best reason to stay with the top loader--You've got a lot of laundry every week and don't want to invest any more than you have to.
Besides, the front loader provides something for your dog or child to watch!