I bought the 128GB version of the JetDrive 360 in on 4th May 2015. I have been using it in my late 2014 MacBook Pro ever since, every day, many hours each day. I use this Mac all the time, and I use the JetDrive as a permanently mounted external drive for storage of projects I am working on as well as my iTunes library. It is usually around 80% full and has honestly proved to be 100% reliable. I have been using it through all of the macOS updates since May 2015 and also several pre-release versions of the OS (I am a developer). Now using it with Sierra 10.12.5.

I was looking into buying a 256GB version a moment ago and saw that many of the top reviews for the JetDrive said it has problems unmounting unexpectedly and/or "failing" early and so on. I have not experienced any such problems and just wanted to add my 5-star review for any of you wanting to buy this cute little device. It fits beautifully and is almost flush with the right edge of my MBP.

BTW, I always put my Mac into my shoulder bag with the JetDrive facing up, so that the weight of the Mac is not pressing on it. It may have nothing to do with anything, but I thought I would mention it anyway.

I really like the concept of what this does. The speed of the transfers writing and reading were as expected (not as fast as an SSD or anything). The only reason why I gave it a 4 star instead of a 5 star is due to the fact that it sticks out (as mentioned in the product description), but that was still too much for my horizontal Henge Docks and I would have to take it out every time I docked my retina 15" MacBook Pro.

I wondered why they couldn't design something to fit in the SD card slot and have it flush, so I ended up attempting to grind down the extra lip and it appears that the microcircuitry inside has no room to spare, as the SD card stopped working after.
WARNING, I got this as a freebie trade and I backed up all my data before attempting this. I do not recommend attempting this as you may waste your money and also lose your data if you don't back it up.

Overall I still prefer my Samsung 256GB MicroSD EvoPlus and a BaseQi aluminum MicroSD adapter. The BaseQi has a little nail-slot to still pop the card out, and it's made of true aluminum and sits flush to the edge.

I have been looking for sometime to expand capacity on my MacBook Pro 15" late 2014 version. There are two solutions available and I choose JetDrive Lite. Below is explanation why:
1. Price
JetLite Drive 360 256GB version has very good value versus capacity. I belie the best you can find.
2. Jet Lite Drive is recognized by macOS as separate drive and you can see icon on your desktop and not like other brand when card is integrated with your existing Mac SSD to create bigger internal drive and shows as a bigger one drive - simply as RAID 0. In that case you will never have control where you data are written - in case of failure you can lose important stuff. This is not a big issue if you are making regular backup but most of people doesn't. I would not relay on this kind of setup and Jet Drive Lite give me full control when I want to put my data - SSD or JetLite Drive.
I could put the name of other brand because when I did my review was rejected by Amazon due to some rules in guidelines. If you will search you will find what brand I'm referring to.

Some reviewers complain that when MacBook is woke up then they can see this drive even with Jet Toolbox installed. I'm using this already 3 months and it happens only 2 times. I just remove and plug back again and problem solved. I'm using macOS Sierra and beside this 2 times never have problem with this drive and for longer time I didn't even installed Jet Toolbox tool.

Hint: if you bought this one you will of course use with your MacBook. Before first use just format to OS file system and Time Machine will backup also this drive when performing regular backup of you MacBook.
Summary: easy solution to expand your MacBook storage (for example use JetLite in your iTunes as default storage for all your music). Even 2 times happened that Drive wasn't visible when after MacBook woke up I still give 5 stars because this drive gave me 256GB more space and working as describe.
Always make sure that you buy right version of JeLite Drive based on type and year of production of you MacBook.
Go to Transcend web site Consumer Products - Apple Solution - JetDrive Lite where you can find table and choose right version for you MacBook.
On the same website you can find many different solutions to expand your MacBook storage capacity.

1/15/207 Update: I bought the 256GB version and for whatever reason I'm having no problems with this card automatically remounting on wake (unlike the 128GB version). I'm returning the 128GB version and keeping the 256GB version. Also, I'm updating my rating from 2 stars to 4 stars.
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I'm bummed out as I really wanted to like the Transcend 128GB JetDrive Lite 360 and wanted it to solve my problem (expanding semi-permanent storage). Unfortunately the 128GB card I purchased through Amazon inconsistently remounts successfully or unsuccessfully upon waking up from sleep on my 2015 15" Retina Macbook Pro (MacOS 10.12.2). I wonder if I got a lemon or if this is par for the course. EDIT: to be clear, I installed the JetDrive Toolbox software on MacOS 10.12.2 and it definitely did not do what it claimed ("automatically eject the JetDrive Lite before the Mac enters Standby mode and remount it when the Mac wakes up"). This may be purely a software issue, but one that renders this storage device unpredictable and unreliable.

I primarily use it as a place to keep my iTunes library as the primary drive on my MacBook seems to get quite full quite quickly. It fits quite snugly and gives me double the storage capacity to lug around. What surprised me though is that its fast enough to run virtual machines stored on the JetDrive without feeling sluggish. I had moved a Windows 7 VM to the JetDrive to make some space on my primary drive and when I launched it from there, it ran almost as quickly as if it was stored on the primary SSD.