My thoughts on the iTens.
I use the iTens and get on well with it. A major plus is that there are no wires attached to it and with the app on my phone I do not have to find somewhere to put a remote control.
There are however a couple of problems, which are more of a nuisance than serious. One is that if the app is not used for 30 minutes the whole thing has to be reset which involves pressing the wings unit. OK if you are at home, but most definitely a nuisance and almost impossible if not.
The other is in replacing the gel pads. They fit the wings exactly, if if they are not positioned correctly the first time you either start again or manage as they are. The very first one I put on was a one or two millimetres out on one side so I dabbed it with talc to prevent it sticking to my clothes, rather than replace it, the next one I got spot on.
On the couple of occasions when I have had to contact the company I have found the staff to be helpful, polite and knowedgeable.
The instructions supplied with the unit are clear and the app easy to follow.