Euthanasia is bad from a practical standpoint, and an evil, because:
1. Objectively speaking, euthanasia is suicide, and the killing of an innocent person. If Schwartz killing himself (out of despair for his future, fear of suffering in prison, or otherwise) was a tragedy, why is Pieter's upcoming suicide not a tragedy? Is it because his certain death is closer? (This view promotes the idea that a "disabled" life, where one is "unhappy", or must be cared for at great expense, or is suffering, or (extrapolating) is cryogenically frozen, is not valuable in and of itself; but it is.)
2. Suicide increases the risk that friends and family will commit suicide. A search will yield numerous studies: "2.1-fold increased risk of committing suicide", etc. If you kill yourself, you are indirectly killing the people closest to you.
3. If you are against the death penalty because we might execute an innocent person, you should be against Euthanasia because we might kill a non-consenting person. This is already the case:
> "these laws and safeguards are regularly ignored and transgressed in all the jurisdictions ... about 900 people annually are administered lethal substances without having given explicit consent, and in one jurisdiction, almost 50% of cases of euthanasia are not reported ... some jurisdictions now extend the practice to newborns, children, and people with dementia. A terminal illness is no longer a prerequisite." 
Please, when you hear someone speak in flowery language about the dignity of choosing death, take a moment to evaluate what they are actually suggesting, and to research why people are opposed. Many seem to think that the only people against euthanasia are the religious whose reasoning is roughly "well, my religion randomly chose to mark this as evil, therefore it is", which is just not the case.
(...finally, this is likely a very poor protocol for dealing with death - people deal in different ways, and not all people will look back fondly on having to smile all the time, or on expressing "false" hope and being told that, actually, objectively speaking, they should not have hope. Also, a totally minor point, but we are not like Lego houses - we do not need to be utterly destroyed for others to live.)
1. Yeah it's suicide. When you live in constant pain, lie in bed, get meds that make you hallunicate and have no realistic hope for improvement that seems like a reasonable option.
2. Suicide usually has some form of emotional component in it that is shared in the environment. That's why we call it euthanasia, it's not really comparable other then the very general "choose to end own life"
3. Sure mistakes will be made. One such controversy in the Netherlands was euthanasia on baby's with an open back (not sure about the translation). If they had a lot of pain or not. In general there are some pretty rigorous procedures in place to ensure we learn from mistakes, and making sure it are honest mistakes.
So point of this reply, it's a two way street. If you have seen the suffering in the end stages of life euthanasia is not a bad thing. Are there drawbacks sure, we're talking about ending a life, no matter what you do there's a stigma involved and because actual human beings are involved it will not always go the way it should.
At the end of the day, the ideal of someone being able to tell the world enough is enough and empowering them to execute that decision, on certain criteria, is a better world then letting someone die in their own feces hallucinating that worms are digging into their feet due to meds and not being able to move due to advanced parkinson. And yes that's the way my dad was in the end before the docter decided to cooperate with his euthanasia.
Sorry about your dad.
>"suicide is better than living like that" - well... yeah, but isn't that always the motive, what's the difference now?
The difference is that the person and their medical personnel are in agreement that realistically: there is not a reasonable hope that their medical condition(s) may be cured or alleviated, so the overwhelming likelihood is that they are going to die from their medical condition(s), and their experience leading up to their death is going to be agonizing and severely depriving of dignity.
With suicide, a person is choosing to take their own life even though they don't have a medical consensus with a reasonable expectation that they are going to die of any condition (besides old age--which I don't believe is commonly a major factor in suicides and would probably not be acceptable).
> well... yeah, but isn't that always the motive, what's the difference now?
See the reply of djokkataja, it covers it pretty well.
> And for (2) "sometimes, mistakes are made and people die who shouldn't have" - is that what you also think when it comes to, say, the death penalty?
There is a world of difference. Now let me say that we in the Netherlands have no death penalty, but let's take the model in America vs the process of euthanasie in the netherlands.
Deathpenalty -> Subject is not willing, evaluation is done by non trained experts (jury) on issues of law (ie guilty)
Euthanasie -> Subject is willing, evaluation is done by trained experts (at least 2 GP's) on medical issues.
In the deathpenalty scenario the worst you can do is kill someone innocent. In the euthanasie scenario the worst you can do is kill someone with a huge medical condition that for all appearances it seems to be terminal with an unbearable standard of living (ie pain).
Comparing the two is cheap rhetoric as far as I'm concerned.
1. This is a tragedy of a death of a human being and the loss for a family of a beloved one - all caused by a disease, not by a "suicide".
2. Those statistics are for overall suicides, not medical assisted ones. Even if they were for medical assisted "suicides" you would need to control for other factors.
3. Medical-assisted "suicide" is voluntary, not imposed by a third party. Its people like you, with your extremist ideas, that are imposing something by denying others the right to choose.
4. This is really not the time nor the place to discuss these ideas. Have some respect please.
It isn't extremist to say that it's always wrong to kill an innocent person even if that person asks to be killed. When I was a kid watching silly movies, I knew that you could shoot a dying dog, but that it wasn't right to shoot a dying man. This was because humans had a certain dignity that put them above animals, even if they had to suffer for it.