Ok so my Dad needed a MicroSD for his GS3 (Galaxy S 3) because he was using way to much space with videos and pictures; he isn't one of the most tech saavy people in the world so I got this for him. Does it work yes it does and very well I might add. Like I said my Dad doesn't work to well with tech and if a MicroSD slowed his phone down when it saved pictures or videos or ran apps from it he wouldn't be happy and wouldn't know what to do with the problem. This card experiences no lag (3 months in) the UHS-I speed class really lives up to its potential here. Best of all, perhaps a little known fact to most of you, this card is waterproof, so you get your phone wet and it dies, don't worry this card is still perfectly fine just pop it in a new phone and there's all your stuff! No cons as of yet will update as needed.