We don't have cable at home; our summer place has Comcast (the account's in my sister's name, I think), but it's too far from Philadelphia to include NBC Philly (but has ROOT out of Pittsburgh, notwithstanding that it's northeast of Williamsport), so I have no experience with that. I did make some (desultory) efforts to use that Comcast account info to access NBC Sports Olympics coverage at home, without much success.
If you're outside the blackout area, and have the hours to devote to watching games (radio still has the advantage that you can have it on while doing other things, and still get a reasonable vocal description of the game), I agree that it's a good value. As a tool for viewing delayed telecasts, it's OK - but I don't know that "incredibly good value" describes it as much as "not that expensive for an indulgence" (for me, at least).