I have been a subscriber to the MLB.TV Premium service for a number of years (I think this year will be my fourth season), and I have been consistently impressed with their service. As a subscriber, I have access to every single game played throughout both the regular and post seasons, both live-as-they-are-played and as archive games after the fact. I can also watch 30 minutes "condensed" games that include just the scoring plays without having to watch the full 3+ hours. This year, I can even choose "home" versus "away" coverage of any given game. As a fan of Don and Jerry, I like to watch the Red Sox on NESN when I can…
One things that really stands out this year though is the quality of the streaming video. It has taken quite a leap forward in my opinion. Using a browser plugin called "NexDef", they are now streaming super-high quality video. While I was watching the Red Sox beat the Orioles this morning, I thought I'd take a snapshot of the difference between the "old" service and the "new" service – you can really see the difference in the crispness of the text.
The NexDef plugin also includes adaptive streaming, so that it can deal with temporary bandwidth issues gracefully. It does seem to eat a little processor when running full screen, but I suppose that is expected given the video quality.
Anyway, if you're a baseball fan and you don't live in the USA, get yourself a subscription to MLB.TV; you won't regret it.