Orcs should be of taller stature and significantly more muscular than the other races. For facial features, personally I would much prefer a "warcraft" style of nose as opposed to a decidedly (and traditional) porcine nose. If I have to look like a walking green pig, I probably won't play one - and be extremely disappointed.
They should also have significant bonuses to axes or two handed weapons. I really liked the look of the concept art for the Orc Armor in thehttp://www.gameinformer.com/b/news/archive/2011/01/26/the-art-of-skyrim.aspx feature on Game Informer, so I think we're good there.
http://us.blizzard.com/en-us/community/fanart/index.html#1182 would be a good idea of how I would make my orc. I'd probably go with a more grey colored skin instead of green-green, and I would tattoo the eff out of him, but you get the idea. Also, a huge axe or maul.
Yeah, I always liked how Blizzard portrayed their orcs. If you think about it, TES orcs and Warcraft orcs are rather similar in terms of culture, in that they are not savage beasts but warriors following a code of honour, they look barbaric but are actually civilized once you look past first impressions.
At any rate, I like that picture. I don't think Bethesda should blatantly steal the look of the Warcraft orcs though, some identity is necessary, but I definately think the orcs from the Warcraft universe are good as guidelines.
How very constructive.