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I bought this for my phone about a year ago to store photos and music on and its done the job brilliantly.
I am still, after however long they've been around, impressed by how small they are compared to how much they can hold. And 2Gb is one of the smaller ones these days. It is tiny. Maybe littler finger nail sized and can hold maybe 700 songs in mp3 format or 2000 photos. All this for about £4 depending on where you go is very impressive stuff.
To be honest I think all brands of memory card are much the same although the M2 is sony's own format. My card has lasted a year with music, photos and data regularly being transferred backwards and forwards and has not yet had any problems in terms of corruption or loss of data. Using a USB 3 port transfer speeds of up to 20Mbps are possible and this means that its relatively small capacity is not a problem as it takes only a few minutes to change all the data on it.
If you have a phone or camera that takes this cards you don;t have much choice in the matter but if you are considering a device that requires a Sony M2 card then don't let the less standard than others format put you off.