Piperazines are a hit or miss, some people have really bad reactions to them, others are perfectly fine taking them. I'm lucky to be one of those people that doesn't have a bad reaction to them. I don't like pipes TBH, I don't hate them but any fun they may produce is generally not worth the side effects they produce.
If you know you have a pipe pill before consuming it and know not to expect MDMA-like effects, then you have a way better chance of enjoying yourself...It's like a psychedelic in that your mindset is almost everything.
The first time I got piped, I was fairly new to testing pills and when I tested them, the reagent turned reasonably black, but it took like 30 seconds to get to that point, so I just figured they were weak rolls, so I ate like 3 to begin with; it basically just ended up feeling like a tease roll, I would start to get tingly and my eyes would slightly wiggle for just a second or two, then would go away, so I figured I needed more, and ate more, but never got a real legitimate "roll" feeling out of it, I gave up on eating more and ended up awake for the next 2 days off of those pills. And as much as it sucked being awake, it didn't bother me that much. Other people though, will get all kinds of crazy side-effects like intense nausea, body-temp issues, etc., I'm lucky enough to not get bad side effects, other than inability to sleep.
Though there was one time I had pills I knew were pipes but decided to take them anyways; I took one and went to bar by my college and I really enjoyed my time; I was social (not lovey dovey), energetic, danced a bit, I just really had a great time, it just sucked when it came time to call it a night and all my other friends went to bed, while I sat in the living room for the next 8 hours smoking obscene amounts of weed and cigs, watching extremely dull TV trying to make myself passout with no success.
So IMO pipes are a hit or miss...if you don't have a bad reaction to them, then I could see people liking them, but with how many people have adverse reactions, it's kinda a tough gamble to make. I guess my best advice would be that if you're going to try taking them, know not to expect a MDMA like experience and take it for what it is; as much as ppl try calling pipes "fake XTC" it really is not like XTC, it has about as much similarity to MDMA as a dose of shrooms does. But don't rule them out completely cause so many people dislike them, take 'em for what they are and if you like it, you like it, if you don't , you don't.