Dragons and Dragon Riders/Tribute Spirits

Ascension of the Dragons introduced to us the concept of tribute spirits, as well as the dual core dragons and their partner dragon riders. I'm just going to ask: how good are the dragons, dragon riders, and tribute spirits? I must admit, I'm fond of some of the riders (Azure because of mill and Grun because of core gain), however, I don't have much experience with the tribute spirits like dark sieg (the only ones I have are the 6 dragons). Are playing these tribute spirits worth it, or is summoning them just a waste of cores?
Just wanted to know your opinions.
PS, I'm not fond of the dragon spells either. They're the only card I'm wishing not to get when I open a set 4 booster pack.

I think in a few decks they may be good but in most general decks they are way to hard to get out and easy to get around if you have a good deck and the right amount of player skill.

The reason I ask, is because the tribute guys sound good on paper, however it may not be as good when in an actual battle.

I thought the dragons/dragonriders had lots of potiental when the set first came out but as our team tested the decks for the new set we realized they did just sound good on paper.