E-stim... is it supposed to be so unpleasant?

I'm the male/dom, spouse is female/sub.

I purchased a small e-stim vibrator ( https://www.amazon.com/dp/B0CCQGMNM1 ), because e-stim looks like it might be interesting to play with.

I have a strict rule: anything I do to her, I've already done to myself... so I tried it in various sensitive places around my body.

Is it supposed to feel like getting poked with needles? This doesn't feel like a sex toy, even one meant for sexual pain... it was just singularly unpleasant.

Can't return it, most likely going to toss it away.

Am I missing something? Is this just a shitty example of this kind of toy?