Update 9/22/14: This band is still going strong - I use it a few times a week and after a year of use, the quality of the materials is still holding up well. I have a Galaxy S5 with an Otterbox Commuter and I can squeeze it in to this band, along with a key and my ID, but probably should just get a new one in the right size!
The inside of the case stays dry no matter how much I sweat, and the Velcro still holds the band tightly as it should.

I had the Razr Maxx and the Otterbox Commuter and the Defender cases - the Otterbox Commuter fits nicely in the armband, with room to slide an ID and a key into the pouch as well. The Defender case is really a tight fit - the phone and case fit into the armband's pouch but there's no room for anything else.
I just went for a run and it held the phone just fine without slipping on my arm. I have an 11-inch (28cm) bicep and the band fits perfectly, with about an inch (2.5cm) of velcro remaining.

I can use the touchscreen through the plastic cover. The side buttons on the phone are easy to press through the neoprene.
I have the Jaybird Freedom Bluetooth headset (an awesome headset - see my review), and it works well with the armband - the headset doesn't cut out at all, and I love that I can control the music player and answer phone calls with the headset, so I don't have to use the phone to access the functions.
This is a nice armband. It feels like quality construction and quality materials. My only concern is the velcro feels like it won't last long. I'll update my review after a few months of use.
Update 9/22/14: This band is still going strong - I use it a few times a week and after a year of use, the quality of the materials is still holding up well. I have a Galaxy S5 with an Otterbox Commuter and I can squeeze it in to this band, along with a key and my ID, but probably should just get a new one in the right size! The inside of the case stays dry no matter how much I sweat, and the Velcro still holds the band tightly as it should. I had the Razr Maxx and the Otterbox Commuter and the Defender cases - the Otterbox Commuter fits nicely in the armband, with room to slide an ID and a key into the pouch as well. The Defender case is really a tight fit - the phone and case fit into the armband's pouch but there's no room for anything else. I just went for a run and it held the phone just fine without slipping on my arm. I have an 11-inch (28cm) bicep and the band fits perfectly, with about an inch (2. 5cm) of velcro remaining. I can use the touchscreen through the plastic cover. The side buttons on the phone are easy to press through the neoprene. I have the Jaybird Freedom Bluetooth headset (an awesome headset - see my review), and it works well with the armband - the headset doesn't cut out at all, and I love that I can control the music player and answer phone calls with the headset, so I don't have to use the phone to access the functions. This is a nice armband. It feels like quality construction and quality materials. My only concern is the velcro feels like it won't last long. I'll update my review after a few months of use.