I would say yes and would recommend going with DL, DA and TA. I think it's called the Utimate Bundle or some such thing. I bought mine differently, but there are some savings if you get the whole thing at once.
Personally, I went with the Gold Edition, whigh included DL and DA and I started with DL. That way, I got to play the first game and had a new game waiting in the wings when I got bored with the first. It took me quite a while before I started playing DA and when I did, I bought TA. I haven't gotten to TA yet because DA still holds my interest. TA will be like having yet another new game when I get around to it.
Pretty good value for money if you ask me.
Beware though. It's addicting.