I do completely agree with Freidus, the Orcs in the Hobbit were well-rounded characters that really gave off the feeling of being actually...well, characters.
While I utterly love how LOTR portrayed Orcs, as said in the Hobbit they are more...I daresay real, and really gave off the feeling of being threatening. Not creepy or scary, gotta give that one to the Moria Orcs, but a threat in the military sense, plus a threat that has a mind of its own; true, they are slaves of the Dark Powers, but a slave's not a robot, having a mind of his own, and they managed to remain a threat enough to unite under an Orc leader and wreack havock without any fallen angel/god directly guiding their hand. Plus, gotta hand it to Azog and Bolg, they were the only villain Orc to last more than one movie XD (there could be Ugluk, who was technically present in FOTR, but was not seen until Two Towers)
About the Black Speech, I believe it does tie things together and indeed fleshes out their culture, and still Fredius is right when he says it makes them more threatening than speaking english/whatever other language. Technically, it makes them completely inhuman (which was the conceptual purpose behind every single evil race movie-wise, harad and rhun included), but to a bad inclination, unlike Elves that are also more than human, but look fair and do speak languages of Men.
Its kind of a different, more daring approach to the matter than LOTR, but I like both of them anyway