I think those of us on the spectrum CAN feel joy and anger and all that, but we get it from different things that the NTs get it from. For example, we might not be really upset when someone we know dies because or we might not feel very happy about marriage or graduation. What we do get hyper about, is the things that we're reaslly interested. For example, I have an Aspie obsession with the rock band KISS and, when their original guitarist Ace Frehley announced that his new band was coming to my area, I was very excited. And, while the concert was going on and after it was over, I was on an emotional high that lasted for several days.
Another thing, if you have a crush on somebody, your Autism or Asperger's Syndrome will make you even more obsessed with that person. So if he/she tells you that he/she loves you right back, I think you will feel overjoyed and on top of the world. If he/she tells you that he she does not feel the way you do, you will experience the heartbreak that NTs do, maybe even worse.
But, I think we just experience the emotions from different things than the NTs and, when we experience them, we experience them stronger than the NT does.