I bought the 64GB version for my Samsung Galaxy Note II and it works great.  Didn't need to format or anything.  Opened the box, popped it into my phone and it worked just as expected.  Transfer speeds via usb connected to the phone and direct via card reader are both fast.I also bought the 32GB version to use (with included SD adapter) in my Canon SD4500IS.  Again, just popped it directly into my device and it was ready to go.  Very happy with both products.  I've used many Sandisk flash cards in the past without issue so I expect these will hold up extremely well over time as well.  It might be a few more bucks than some lesser known brands, but I feel its worth the premium.