This is so handy.  I get about 175% charge on my Nexus S 4G (which admittedly has a battery on the smaller side compared to most phones today).  I use it when I travel and it works awesome.  I bought it before they changed the look/features of it and it looks even better now - the battery itself uses USB to charge (why didn't they do that in the first place?).  After dozens of uses, it still charges just as much as it did on the first day (I've had it for 5 months).