An ordinary consumer
Since there are almost three thousands reviews already, I bet almost everything about reading and writing speeds have been covered. I'll just try to provide some specifics from my experience in case if somebody is searching with these keywords. I've copied some WAV and MP3 files to this card from a fast PC (3.4 GHz, 16GB RAM, 7,200 RPM HDD, 64-bit Win 7, etc.) with a built-in card reader. The card reader maybe my bottleneck. Anyway, the observed average writing speed was around 9.5MB/s.Tried this card in Nokia 3555b. Logically this phone cannot read more than 8GB MicroSDHC cards, but it it. However, it saw the card as being only a 2GB card. Tried inMotorola Flipout Unlocked GSM Quad-Band Android Phone with Bluetooth, Camera, QWERTY Keyboard and Wi-Fi - Unlocked Phone - US Warranty - Black. Played those WAV and MP3 files and it worked very well. Tried inMotorola MB520 Bravo Unlocked Phone with Android OS, 3MP Camera, FM Radio and GPS - US Warranty - Blackwith the same files, and it worked well too. No hiccups. Then inserted (and left it in) inBLU Studio 5.3 II Unlocked Dual Sim Phone with Dual-Core 1GHz Processor, Android 4.1, 5.3-inch IPS Capacitive Touch, and 8MP Camera - U.S. Warranty (Black). So far so good. Will update this review if problems will arise.It was sold and fulfilled by Amazon in a frustration-free packaging. I love this packaging not only because it does not have nasty blister pack that cuts your fingers, but also because it is eco-friendly.