A few thoughts:
Druid -- I added two eggs and a poison seeds to my token druid deck. Generally, it seems pretty good. I had added a MotW for an Egg, but took it out fairly quickly. I can activate an egg with Wrath, but generally he's AOE protection. As for Poison Seeds, it's pretty good as mass big minion removal, and it's pretty neat with the egg. I had a combo going where I cleared his strong board and replaced with treants, but couldn't draw a Swipe to save my life to match up with Kobold. On a even board with egg, you get matching treants plus the 4/4 spider. Neat.
Rogue -- the 5/5 for 4 is pretty nice. Better than Yeti as a body. The deathrattle is more annoying than I thought, though. One thing I learned -- Sylvanas's deathrattle will steal your minion before it gets returned to hand by the deathrattle. Lame. I got Alex back in my hand once, as well. Still, I like it.
I added the spiderlings to my warrior deck, but dropped them.
On Maexxna...I'm torn. I've gotten good use out of her multiple times, as she's pretty good for board clearance. In my rogue deck, which is decidedly lame anyway, I was able to Maexxna, deadly poison my hero dagger x2, blade flurry to clear the board. And then sometimes she's just lame.