Minerva's Den was definitely worth the price. As for the other DLC's, they're not worth it in my opinion. If you're a completionist and need the DLC achievements or if the DLC is discounted at a reasonable price, then go for it.
thread determines the quality of Minerva's Den.
163/164 games completed (including DLC)
Completion percentage: 100%
Latest retail completion: Dragon Age II
Latest arcade completion: Dust: An Elysian Tail
Currently Ranked #1 on Achievement Completion Percentage Leaderboard on TA