Ogre Kingdoms are larger than man-sized people who live up in the mountains. Practically every unit has the 'Dogs of War' special rule. This means you can normally field an Ogre unit in any other army that has 'Dogs of War' as a rare unit. Ogres are all S4, T4 and have 3 Wounds a piece. And that's a core choice.
Also built into every Ogre is the Bull Charge. If an Ogre charges more than 6 inches (since its movement value is 6, they have a full charge range of 12 inches), each Ogre in contact gets an impact hit. Plus every Ogre in the second rank grant +1 S to the impact hit.
Big dudes, cool rules, lot's of wounds. So what's the draw back? They are very expensive points wise. A normal Ogre Bull is between 35-43 points depending on how you outfit them. So if you want two ranks of Ogres, you're pumping a lot of points into one unit. The other issue is survivability. Ogres are T4, yes, but have crazy low armor. Ironguts have Heavy Armor but wield great weapons so they have to balance. Their magic, while really funny sometimes, is usually pretty weak. All Gut Magic spells cast on a 3+ but that also means dispelling is usually pretty simple.
I'm still excited about seeing Ogres in 8th Edition. I loved my Ogres when I got started. With the rumors of an additional attack at the end of combat from larger models, the old Ogre list is starting to creep back into my mind. I can see it now: the 3x3 formation of Ogre Sized units running down small units and taking their lunch money. With the additional rumors of Ogre Sized models in the second rank getting up to 3 attacks instead of an additional 1, that's quickly becoming 3 Impact Hits at S6, 18 attacks at S4, and another possible 3 Stomping Attacks at S4. Start adding command and heroes to units like that and Ogres get a new lease on life.
I first started out in Fantasy with an escalation league with my Ogres. Escalation leagues are a fantastic way of starting a new army or even a whole new game system. So if you're thinking you want to get into Fantasy when the new edition comes out, try an Escalation league. If there's enough interest I'll post on how to run one effectively for Fantasy. And remember, a lot of GW's already have the new book. Some of them are even going to be running some demos of the new rules in the coming weeks. Ask them and see if they're hosting a preview night. Until then, stomp ya laters!