I had before and now the GS2 SG4 ... the batteries do not hold water! I wanted to retry the experiment, but even new, the battery does not compete with an original battery slowing after a good year ... I recommend on having two batteries (to change in case the original is empty before the end of the day) but certainly does not replace the original one!
A little more per cons on customer service remains visibly listening to customers and enjoys a good reactivity still ...