Did a lot of research before buying this. I ran out of space on my iPhone sometime ago & was getting fed up of having to delete stuff off before being able to add something else on. I looked into the Kingston alternative but that wasn't a huge amount of more space (I have a lot of video) & not expandable. The Seagate Satellite Go-Flex looked good but for every good review there was a bad one so I held back from buying one although it seemed the better solution compared to the Kingston. Then, by pure chance I found out about the Airstash. I looked at the reviews (there are loads on Amazon.com) and took the plunge. I have an iPhone 4 & an iPad 2 and it works great with both. Download the free Airstash App on iTunes - it works really well. You can use their web browser too but is is not as slick (you will need it however to set your 13 digit WEP key initially). Here is a run down of the pros & cons:
Pros:
-It is very small (bit like a fat USB stick
-If you run out of space on the SD card-just pop another one in. You don't need to switch it off to change cards, just stop any current tasks-pop the card out, put the new one in & click the 'refresh' symbol on the Airstash App
-It works GREAT, my videos streamed really well with no noticable deterioration on quality. It also remembers where you are in a film & will ask you if you want to start from there or go back to the beginning which is cool.
-It will stream to more than one device
-It works in conjunction with Goodreader amongst others. So far I have downloaded an MP4 file and pdfs into Goodreader, than transferred those to the Airstash.
-It takes any type of SD card, including the latest SDXC cards which can go up to 2TB. (However the largest available at the moment I could find was 128gb)
-As the Airstash will take any type of file (playback of files is only limited by the device's limitations) - if you want to play other formats such as AVI files or FLAC files for example, you can download apps such as OPlayer which to play such files stored on your Airstash on your iPhone/iPad etc
-It will charge using your iPod USB mains charger:-)
Cons:
-As it is wider than a normal USB stick it can block access to other usb ports if they are in close proximity.
-As the Airstash is essentially WiFi router, as soon as you connect to it, you are disconnected from your home WiFi network. (This is being looked at in a future firmware update I believe)
-The Airstash currently only supports WEP - but does support WPA2, which is also promised in a future firmware update.
-Says it works
-Obviously, it takes a little more time to watch a video for example, than if it was already on your device. The steps would be: (1) Turn on Airstash, (2) go to settings & select the Airstash wireless network (if at home, if out and about it will pick it up straight away so you can skip this sep) (3) Open Airstash app (4) Select file & play
In short, this is a great piece of kit. In the past I have always bought the largest capacity device as I worried about running out of space, however now I will just get the smaller size that will take my music & apps and store all my videos on my Airstash.