I had this little guy for roughly a month now and it's working great.  I'm using it to charge up my nexus 5 and it does the job.  It's small and compact so it's a perfect fit in my bag and I would carry with me all the time in case I ever run out of battery.  The best part about this is that it can charge up to 2-3 full charge.  I remember I was hanging out with my friend one day and I charged up her iPhone 4s and then my Nexus 5 the same day and both phone got full charge.