here is a post by K'dOUTinAZ that I feel sums up meth, this was taken from 'Cocaine or crystal' thread
Methamphetamine on the other hand is a whole different story. One gram of meth will keep you awake for a couple days, that is for sure. Snorting and smoking meth are two totally different highs but I would suggest snorting it. One thin two inch line will keep you wide awake for a few hours (75-100mg). It will burn! You will feel an intense rush go up to your head and will feel jolted from where you are. A warm tingly sensation will be rushing through the back of your neck and yur eyes will dialate. Sense of well-being, euphoria, loss of appetite, significant increase in energy and senses, and increased concentration are a few of the things that will follow. Many people react different, especially those that have ADHD I have noticed. Many tweekers I know have an increased sex drive and lovey-dovey feeling while on meth, I have the opposite, no sex drive and superior to others (as in, if someone fucks with me, I will kill you or send the shadow people after you). This brings up another effect of meth, hallucinations. After up awhile on meth you will see things from the corner of your eyes, glitches I call them. Many people see "the shadown people", shadows on the wall that look like people and are not really there. You will become repetitive over time and look out the door peep hole hundreds of times or peep through the curtains, take things apart and put them back together, etc. After the first day you may get paranoid and start to want to comedown but find it very hard to do so. You may feel sleepy but cannot get sleep for the life of you. Always have sleeping aids, weed, or alcohol available. After you comedown you feel miserable, sleep forever, depressed, you crave more once rested, feel like an outcast, and start to think different. I used meth for about one year but never knew "why" I kept using it, I hated the feeling after while, I just didn't want to sleep for three days straight, unable to do anything once I woke up. I would curse myself out before hitting the meth pipe, it was horrible. BTW, smoking meth is the worse taste you will ever encounter, stale piss, moldy milk, and a bunch of other brutual tastes. If you want to be "different" for a long time then go ahead and give it a try but I wouldn't recommend it. Youloss like 50lbs. within a few months and never sleep so you look very unattractive and pale, sunken eyes.