Is it painful? Yes, though some more than others. Some machines feel like being stabbed with an ice pick, some feel more like a mild vaccine.
Is there scabbing during sessions? Not on mine.
Is their temporary discolouration? I didn’t have any other than the redness, which went away with in about the same time frame as getting waxed.
Does the hair eventually come back once your dead cells regenerate? Hard for me to tell. I had it done when I was 14/15, and it wasn’t completely removed, so between the decade or so since it’s been done, and accounting for generally less hair than at the height of puberty, I don’t know if it really did anything. My mother sure thinks it was money well spent, but on the other hand, she asks me if I’ve lost weight when I’ve actually gained 3 pounds and has frequently fallen prey to the placebo effect, so I don’t know that she’s in any way a reliable judge of the matter.
Is it a better option than waxing, plucking etc? Hmm. I don’t know. For me? It really helps that I wasn’t paying for it, though I can’t imagine myself ever thinking it was a reasonable price unless I was debilitatingly insecure over the offending hair. Waxing I can’t stand; it hurts like the Dickens on me, much more than this did (at least, with the non-ice pick machines). Plucking doesn’t hurt so much, but I also really only pluck the occasional stray. So, really expensive plus lots of painful sessions, and it didn’t even totally fix the problem (but if we had continued, maybe it would have??)... I wouldn’t get it again.