As a TOS-lover, I'd like to defend the original DM sfx... but I can't. Even when I was a kid, I thought they looked bad, particularly the AMT model.
The Cornucopia of Doom was fine though the see-through effect was jarring. The only sfx I liked was when the Enterprise first approaches the Connie, and you see the Connie through the viewscreen with the dirge playing on the soundtrack. *That* was goosebumpy.
As for the new sfx, they looked kinda lame in their own way. Oh well.