Demigryph Knights-are Awesome. They're fairly cheap and have a 1+ armor save. Yes, there's a human riding it so it's T3, but it does some damage. You can take halberds to boost the rider's strength, but I'd keep the shield since the rider's attack isn't the important thing here, it's the mount's. Don't go 2 ranks for the same reason. 3-4 in a unit will do.
Celestial Hurricanum- is one of two new mounts for wizards that are also available as Rares. This one is for Celestial Wizards. It's not bad...a little fragile but has some fun tricks. First, if you take one or more of these you get a free power die, which is good because the big toy for this guy is a bound spell we'll get to in a moment. He also gives a bubble around him with +1 to hit, so again there's the synergy we can expect from Cruddace. The bound spell targets a unit and has a random effect (which I don't like...rnadom is not reliable obviously) that ranges from moistening it (which would be cool if it took away flaming attacks for a turn, but it does nothing) to rotating it to tossing a stone thrower shot into it. These are considered Celestial spells so they get the lore attribute. It's not that I don't like this, it's just that I'd spend my points elsewhere...like a cannon.
Luminark of Hysh- is the other mount, this one for a wizard of Light. It comes with a dispel die and a 6+ ward save bubble. Again there's a bound spell on it that's essentially a flaming bolt thrower, but a Light spell so it also gets the lore attribute. This also represents another cannon and while it's bound spell is going to do damage, I'd rather have the cannon that doesn't use power dice and can't be dispelled.
Helblaster Volley Gun- This one got better. Now you roll 3 artiliary dice...that's how many shots you get. It's BS Shooting still (damn you Dwarves and your auto-hitting Organ Gun). If you roll one misfire, you cut the results of the other 2 in half. 2 misfires is an actual misfire, and 3 gets interesting. It's random and could toss out 2 shots, or it could be pretty awesome. If you roll those 3 misfires, it tosses out 30 shots...and explodes. It was talked up quite a bit when the book first hit, but again I'm not sure I like it. If you do use one, I'd add an engineer for the better BS and misfire insurance (yes, if he choses to focus on this he can do both)
Helstorm Rocket Battery- And another of our big guns got a change. This is possibly a better horde weapon then the mortar with it's unnesessary nerf/points boost but it's still a bit iffy. It can toss d3 small blasts. You pick a target and roll your arty die. That's the distance all your rockets drift. Then you roll a scatter die for each shot. All the shots scatter from your first target. This means if you're aiming for a big unit you should be OK, or if your opponent's packed tight, you can possiby hit multiple units. I'm still not sure how I feel about this one. It's not cheap but it can do some damage.
Steam Tank- Now we're talking. First the negative...its now T6. Not a huge deal most of the time, but it's there. Now the good. It got cheaper, it got more reliable, and if it takes a few wounds, you don't fear generating steam points anymore. The steam gun lost it's no armor save, but the Steam Cannon is now a real cannon. It's still pretty nasty in CC too, and since it moves random, there's no combat reaction but hold so that's cool. It's still a 1+ save and 10 wounds...it's unbreakable and it uses normal rules for stat tests so it's at least a little less succeptable to the big unit deleting spells. It's a great unit and a nice addition to your army.
So there's the Empire. Next time, I'll dive into my own list with the why's and why not's, but for now this should be a good glimpse on what you can do as a fellow General of Men...or lets you what will be trying to kill you in games to come.