A few things, I have chronic muscle cramps all over my body so the fact that these are just 2 pads that I can put anywhere I need them and the heat is instant is a true blessing, no more waiting for a heating pad to heat up at 2am while I am having a cramp in my feet or back or side or neck. Also being able to place the pad and them not move and I don't have to hold them is a game changer! I don't use heating pads for just menstrual cramps or back pain. For the overall effectiveness I give this a 5.My cons:1 - the battery sucks really bad....2 - the low and medium settings don't do much for me...3 - Replacement pads are over $10 each I can buy a brand new regular heating pad for less than a set of replacement pads... Do better Sunbeam!4 - The pads don't last long (10-14 uses is what I've gotten from them, even if they stay sticky they don't get as hot)5 - You can only use 2 pads I'd love to see an option for 4+ pads6 - There is no case to keep everything together7 - the pads don't stay well in areas of the body that have rolls or curvesI use it on high and it feels so good. Yes it is very hot. So much better than a heating pad. I like that I can just put the controller in a pocket and walk around. Now that the weather is cooler helps to just warm me up in the mornings :) I got it to help my back/shoulder muscles relax and it works great for that.Just wish the battery lasted longer or that i would get better about plugging it in when I am done with it.I have been using a heating pad for menstrual cramps to try to cut back on ibuprofen use and it works well, but you’re kind of stuck hanging by an outlet. I was saying to my husband about a month ago that they really need to make wireless heating pads. Well, luckily my phone was listening to me because an ad for these portable heating pads came up on Facebook a couple days later. I’m using them for the first time today and they are a game changer. They were so easy to put together and adhere. They started heating up immediately. I was surprised at how quickly they warmed up. There are three different heat settings. I have it set to medium and it feels perfect for me. One thing that I didn’t think about before using is that you need to charge the unit before use. I opened the package and was ready to use them when I realized (duh) that I would need to wait until the unit was charged. This would work really well for sore muscles as well. I’m really happy with this purchase.excellent item. worth every pennyThe adhesion wears out very fast. Makes it almost not worth it. It also doesn’t stick that well in your curvy partsI have horible lower back pain and a one year old. The other day I was wearing her in her carrier and having to bend over to pick berries. Needless to say my back was super sore later that afternoon. I tried this for the first time and was really pleasantly surprised at the amount of relief I felt with the heat just on the lowest setting. I put it up to medium and then high for just a few seconds each and was surprised at the amount of heat generated. I ended up just using it on the low setting because it worked so well for me. I was also able to go about my day without it getting in my way because the cord wraps around the base and the clip to hook it to yourself. Good buy.Very disappointed. It says charge last 8 hours. Mine only lasted a little over two hours.3 complaints: battery doesn’t last very long, can’t charge and use device at the same time, and replacement pads are expensive. But device is convenient and effective and until something better comes along, I’ll keep using it!