I think it's problematic.
If you read the Bill, it all seems very sensible and full of appropriate safeguards.
Then you get the part about the actual dying. The person has to "self administer" the medication - in wonder what that will actually be like in real life, on the ground? A person may very well opt for assisted dying, complete the declaration to confirm that they are of an informed and settled decision. But when it comes to it - I think it could be messy. The instinct to live is strong and I wonder who will be able to swallow the drug cocktail. Of course they can change their mind at any time. But think there could be messy and traumatic scenes for all concerned.
No one wants to die a horrible painful death but with proper palliative care provision no one needs to. Palliative care doctors titrate morphine to the right level so that the patient is comfortable without it killing them. Of course sometimes the reality is that when someone is in a huge pain they have a lot of morphine and it's perhaps that that makes them slip away. But with palliative care the patient can be looked after, can be cared for in the hands of the hospice - and because death is not an "option" that anyone can actively choose, there is no pressure on the patient to feel that they should "hurry up and die" etc. its a process out of everyone's control and everyone has to let nature take its course.
Once it's in our option/control then I think there are a whole host of complexities.
I don't think "fear of dying in terrible pain" is a good enough reason to back it. If that's what you fear (and who doesn't!!) then what we need in order to deal with that is really good palliative care.
We don't need to change one of the fundamental givens of life/society.