I bought one of these recently in order to use when in Ireland ("feel at home" with Three where you can use your Three mobile in certain countries as if you are in the UK so UK inclusive bundles, rates, etc). It was ideal for what I wanted and enabled me to keep in touch with family by text, phone or internet without worrying about running up an exorbitant bill. The sim card fitted well with the adapter and I was able to use it immediately.
I bought this recently in order to use my MP3 player with my bluetooth headphones. It is even better than I had hoped for. Small and very easy to use. The range was easily 25-30ft indoors. I highly recommend this product.
This headset has very good sound and bluetooth connectivity and is very easy to use. The only reason it isn't 5* is because I find the plastic headband rather uncomfortable as it rests on my head and because the ear pieces are angled in such a way that they don't stay on my ears unless I have the headband resting firmly on my head. I am now looking for suitable padding to stick on to the headband to reduce the discomfort.