Top up TV has the advantage of providing extra channels for a lower monthly cost than standard satellite providers. The disadvantage is that there is an initial installation fee that may outweigh the lower financial outlay. If you are buying it for sports channels then beware that broadcasters can often switch events to channels you may not have subscribed to.
So far, I don't have any complaints. And since you don't have to sign any contract, you're free to stop using their service anytime, so why don't you try? I mostly use it for tv shows, I don't know how ESPN works.
