I own an iPhone 4S but broken and now have my first android phone Samsung S4. Removable battery definitely my reason.Thought I wont like the thickness of the phone with extended battery until own one recently. I ve tried a lot of things to improve its battery life, using apps like Juicedefender and my phone could easily through one day if not using it hevily, however, I always use a lot on it, so I basically swapped a second half day. I have several OEMs, but got my first extended battery (a 7000mah one of mpj) recently. I now kinda rely on extd. battery. It currently gives me a total screen-on time of 7-9 hours. The extra juice is definitely worth the extra bulk and weight nd the added weight and thickness gives more surface to hold on to. Anyone also lean to extended battery? Cheers!