I canceled it a couple of years back. First, you have to have a DirecTV subscription with at least the basic channels package to order Sunday ticket. I could not get HD satellite reception from my location so I went with FIOS. I kept DirecTV basic only for Sunday Ticket. I would suspend DirecTV service for 6 months a year in the off season, but it is still expensive. When I first subscribed to Sunday Ticket I think I paid about $150 a year for it. When I cancelled it I was paying nearly double that WITHOUT HD which cost extra. Basic DirecTV went from about $40 to $70 as well.
The last two years I had Sunday Ticket I was watching games on my laptop or through XBox. The reception in low def on my TV was pretty backwards, although I could see the game, it wasn't HD and I am spoiled. At the same time, the Cowboys were broadcast locally about 12 out of 16 games so I was paying all that money to watch 4 games. I am a big Cowboys fan but that was kind of silly so I cancelled everything. I did get to watch other games but I had it to watch the Cowboys. Keep in mind they do not carry any preseason games, any nationally televised games (like Monday and Thursday) and no playoff games. You only get regular season games local broadcasts.
I am not advising anyone what to do, but for myself, it just became impractical and way too expensive. Perhaps if Sunday Ticket was offered by FIOS or even as a streaming package on Netflix or Prime I might consider re-subscribing. But if it's $250 or $300, which comes to more than $30 a game if the Cowboys are on national TV 8 times I would probably skip and it watch the replays on the NFL channel. To be honest, I prefer streaming to all the cable providers including the satellite services.