I can't take Caffeine without L-Theanine. If I take caffeine alone I bite all of my nails and get a general sense of impending doom along with a shitty mood.
I had heard it was a little more gentle on the stomach and figured it was worth a shot, as caffeine is cheap anyway.
it actually worked as promised, it doesn't bother my stomach as much as a caffeine tablet or regular caffeine powder.
I usually mix it 1:2 with L-Theanine and cap it just like I would with regular caffeine and it gets the job done.
less jitters, less feeling like I'm going to die if I haven't eaten, less stomach unpleasantness. etc.