I am sure they will.
Bioware wanted the abilities to make you feel like they really mattered when you cast them. Even Immolate has been changed, and now feels much stronger with the sound alone.
Reaver has the claw attack we saw in MP, and Devour's animation is a "GIMME YOUR HEART AND I EAT IT" one, so it must be quite fun to do.
yea, I wondered about that as well.
I mean, the first is going to be somethig like the continuous damage aura (a toggle probably). I doubt I'll use that, mainly because I never liked it before, and unless this works off guard as well, health is too precious a resource this time around to actually use that as a minor damage increaser. If the increase is significant however... who knows.
Devour will be awesome. I'm still hoping for a vampire-like neck sucking animation, but I 'll probably be a bit dissapointed there :/ Still, I can't remember where exactly I saw it, but didn't devour have a really short cooldown and high stamina cost? (I think it was a multiplayer video) It'd be nice to have a short cooldown devour. That should also fit together well with the gore and trample update.
Now this is just speculation but I think that reaver claw is the devour animation. I'm thinking the final ability from reaver will be something more like haste the more you kill or damage increase the more you kill... something like sacrificial frenzy in DAII in combination with barrage? gah, This is the most wanted tree for me 
I think the passives will be a combination of the berserker and reaver from DAII. Mainly fervor, barrage, blood frenzy... adrenaline, even? I don't know, I'm just hoping here 