AT LEAST once. Actually, I went twice. The mango lassie tastes really good, it works, too. The tiny and sparsely decorated room's staff is friendly and can help out with all kinds of infotmation. The really good thing about thr Lassie Shop though is that this is just a great place to meet other travellers - and the interesting kind. Plus it's one of the examples where the recommendation in guide books has done no harm. If I should ever return to Jaisalmer, I'd pay this establishment yet another visit.
PS: I hope Tripdavisor will soon change the name of this establishment on their website, as a new shop has opened who have taken over the name "Bhang Shop" from the original place.