It hits smooth for me, but I'm a 20+ years joint (weed+tobacco) smoker, so YMMV.
The 2 friends that tried the spice in it didn't report any special harshness, only 1 of the two couldn't hit it right the first time, he toked to slow and burned his lips with the hot air. But once you find your way around, it's all good... Takes a couple travels to get used to.
I wouldn't recommend the use of a jet flame lighter, unless you want a) to break the glass and b) to burn yourself dangerously, as you'd have to direct the flame to your mouth !
A bic lighter seems to work perfectly, with no bad taste. Just be careful to not get the Glass Bat dirty with soot.
A Zippo is out of the question, the flame is too big, not stable enough and stinks like hell... well like naphta