They have 3 more coming out that will be released over the next 3 weeks (next one comes out in roughly 24 hours). Each one will come with (I think) 3 neutral minions, 2 class minions, and a legendary. They are $7 each or you can buy the remaining 3 for $20. Or you can buy for 700 gold each.
There are some cards coming that will change things a lot more. The first batch of cards weren't that important... Egg is obviously useful for zoo, and Weblord is good if you play against a lot of zoo. Poison Seeds is useless, and the 4 mana 5/5 for rogue isn't very useful.
The next legendary is a 5 mana 5/5 that increases the enemy's spell cost by 5 mana on that turn. So for instance if you're playing miracle, if they drop a gadget, all you have to do is put him down and you can block their entire gadget turn. It's obviously going to be useful to block soulfires, paladin heals, it will give you another turn to kill a mage, and so on.
Anyway go read the
wiki, there's a lot to get excited about IMO. We only saw 6 cards of the 30 or whatever that will be released. Not every card is going to be useful, but a lot will.