Rasmus,
First you need to ask yourself, "Self, why am I subscribing to Don Best?".
If it is to catch line-moves prior to a local moving, then it is likely worth it. Even though, as pointed out later, I consider any particular line to be suspect, as a whole, if you see a lot of books move, the line is moving.
If it is just to get an idea of what the available lines are, then it is not worth it.
As others have reported, there are concerns over the validity of the injury data, but I also think that a lot of people overestimate how much "insider information" there is - a lot of times, players really ARE gametime decisions, and reporting it while it is being announced on TV is the best that anyone will be able to accomplish.
Personally, I use the free version, and will until they address some concerns I have - I do my own handicapping, and get input from others, but don't play just off of line moves.
The biggest problem / concern I have with the Don Best service is that even the LINES which are reported are unreliable, and, to the best of my (limited) knowledge, they have done NOTHING to discourage books from playing games with the lines which are reported on Don Best. This happens a LOT in the early morning hours with overnight lines, but happens at other times as well.
I have written several times to Don Best saying that I would be very likely to subscribe if they could explain to me what actions they take when they receive reports of a book having a different line than is being reported on Don Best, or what they do to make sure that books report to Don Best the same lines which they are actually using to book wagers.
The most recent time I wrote was during March Madness when Don Best were running ads indicating that 1/2 point could make a difference (I agree with that).
They have NEVER replied to my e-mails, which, IMO, says a lot.
Good Luck,
Bart