They do give the best high when used correctly. The problem is 'correct use,' since they generally require more presence of mind to operate than a bong or a pipe. A problem with vaporizers is that only leaves in contact with the heating element get hot. Most users, in an effort to heat-up curled leaf edges and higher layers of leaf, tend to overheat and consequently burn the stuff. This is not disasterous since you are now 'smoking' not 'vaporizing' the pot, releasing just as many carcinogenic tars as when you light up a bowl.
Vaporizers sometimes fail to satisfy longtime smokers who associate burning lungs with getting high.
They distrust the incredibly smooth taste of the vapors, and they don't like waiting 20 seconds to 1 minute for each hit. My first vaporizer died after almost 4 hours of constant use at a party. I sat in the corner of the room watching them, stoned out of my gourd and filled with happy engineering pride at my creation. Just build an enclosure around it that allows air-flow for the flame, and keeps the 'bowl' high enuf above the flame so that you don't begin burning the pot. Would some Mech.