I must say that my experiences with methadone differ from what some of you are saying.
I was introduced to methadone by a person living with me at the time who took much too many prescriptions and was in general a not so good person. I needed some sort of pain relief. He produced two 10mg methadone pills, I swallowed both of them and felt absolutely nothing except maybe a slight bit of restlessness.
A few months later I was making a trip and suffering from a work related accident. I called a friend to find out if he could help me make the trip in comfort, and he told me all he could provide was methadone, but at a very cheap price (I believe he gave me 15 10mg pills for 50 american) I decided that maybe all I needed to do was up the dose from 20mg to 30 or 40 and I could give or throw the other pills away. After imbibing 3 pills and feeling nothing I took a 4th and began to experience a decidedly euphoric opiate sensation building in myself. It never seemed to get stronger after an hour or so, so I said what the hell and ate two more pills. By the end of the car ride I had eaten 10pills and only barely managed to arrive at my destination unscathed. I wandered inside and proceeded to spend the rest of the night hallucinating in a warm bubble of opiate bliss. The next day I felt like I had taken a good dose of morphine and I also experienced a good deal of vomiting. Towards the end of the day I began to feel worse, but a buddy came over and suprised me with a bit of cocaine. I snorted maybe 5-6 gram sized lines over the course an early night, and felt fantastic all the way through even the come down. I was returned completely to baseline.
Neway, just wanted to say that yes indeed methadone can get you extremely high. I had no real tolerance to opiates when I took this stuff because I never take them unless I am in great actual pain.