This is a very controversial question. You will hear good answers and perspective on both sides. In my opinion, we should not allow for euthanasia for several reasons.
First, we should uphold the sanctity of life. Moreover, we have such an individualistic worldview that we think that we live for and to ourselves only. However, there are others we need to think about as well. In light of this, I have a hard time absolutizing the individual. Tied in with this is the idea that there is no reversing death. There is a finality, which cannot be undone.
Second and perhaps more importantly, where do you draw the line? Would we be opening up a can of worms that should not be touched? This will be a huge ethical question with lots of slippery slopes. And all line that are drawn would be cultural and open for debate.