Read performance is great -- using the included USB reader I was able to get 140MB/s read. Write speed on the other hand is disappointing, again using the included USB card reader, I was only getting 40MB/s.

Update: retested this on a PC running Windows 10. Previous test was done on an iMac and I mistakenly made the assumption that the test result on iMac would be comparable to test results posted by others using CrystalDiskMark. A sequential write speed of around 60MB/s was obtained on a PC, making it a significant improvement of write speed over the blue colored 633x card. I am updating the score to 5 stars.

Realizing that the benchmark results posted by other folks are not necessarily directly comparable to mine I set out to create a comprehensive list of current microSD cards on the market. The results are below.
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I had the opportunity to compare the performance of the fastest microsd cards currently available from top manufacturers. All cards mentioned in this review are obtained from Amazon during the last week or two except when noted otherwise.

Test Setup:
Lexar Professional workflow UR1 microsd card reader was used for all tests except when noted
CrystalDiskMark 5.0.2 x64 was used to produce all the test results and was set up with 2 passes and 100MB read/write size
All cards up to 32GB are formatted as FAT32 with 32KB allocation unit size, all 64GB cards are formatted exFAT with 128KB allocation unit size

Test Results (Numbers are Sequential Read, Sequential Write, 4K Random Read, 4K Random Write in MB/s, speeds greater than 10MB/s were rounded to the whole numbers)

16 GB Alphabetically
Lexar 633x** -- 88, 25, 8.7, 1.2
Panasonic U3** -- 93, 42, 11, 0.7
Sandisk Extreme Pro -- 95, 80, 7.6, 2.6

32 GB Alphabetically
Delkin U3 -- 93, 59, 11, 0.6
Kingston 90R/80W -- 93, 58, 11, 0.6
Lexar 1000x -- 90, 57, 10, 1.4 <== the listed product
Lexar 1000x with Bundled Reader* -- 148, 60, 10, 1.4 <== the listed product
Patriot EP -- 90, 35, 10, 0.6
PNY Turbo Performance -- 91, 55, 6.9, 0.9
PNY Elite Performance Lime Green -- 94, 55, 7.4, 1.0
Samsung Pro gray -- 92, 82, 10, 3.6
Sandisk Extreme Pro -- 94, 87, 9, 3.0
Sony up to 95MB/s -- 91, 51, 4.8, 0.9
Transcend Ultimate 633x -- 93, 85, 8.1, 1.4

64 GB Alphabetically
Delkin U3 -- 94, 27, 13, 0.3
Kingston 90R/80W -- 94, 25, 13, 0.3
Lexar 1000x -- 92, 56, 12, 1.5 <== the listed product
Lexar 1000x with Bundled Reader* -- 153, 66, 11, 1.7 <== the listed product
Patriot EP -- 81, 22, 11, 0.6
PNY Turbo Performance -- 92, 54, 6.9, 0.9
PNY Elite Performance Lime Green -- 92, 54, 7.5, 1.0
Samsung black -- 82, 20, 8.8, 2.1
Samsung Pro gray -- 90, 80, 10, 3.5
Samsung Pro+ *** -- 92, 86, 10, 5.3
Sandisk Extreme Plus**** -- 92, 58, 10, 2.8
Sandisk Extreme Pro - 97, 91, 10, 3.0
Sandisk Ultra ***** -- 46, 16, 7.0, 2.1
Sony up to 95MB/s -- 92, 49, 5.2, 0.9
Transcend Ultimate 633x -- 93, 83, 7.3, 1.4

128 GB Alphabetically
Lexar 633x -- 78, 28, 3.3, 1.4
Sandisk Ultra -- 92, 19, 6.4, 2.4

* The Lexar 1000x card is the only UHS-II card available and tested, the bundled USB reader has extra pins for reading UHS-II card
** Came bundled with a device
*** Purchased from a large west coast electronics retailer. This card is a new release and not currently available on Amazon. It is different from the gray-colored Pro card
**** old model tested, not the current U3 model
***** old model tested

Fastest Sequential Read:
All tested cards were able to accomplish > 90MB/s, with the Lexar 1000x able to take advantage of UHS-II speed when using the bundled USB reader and leading the pack

Fastest Sequential Write:
Sandisk Extreme Pro, Samsung Pro+, Transcend Ultimate 633x

Fastest Random Read:
Kingston 90R/80W.

Fastest Random Write:
Samsung Pro+

Best overall:
Samsung Pro+ and Sandisk Extreme Pro

Other observations:
Performance and price are not proportional when it comes to selecting a microSD card. Some of the worst performing cards in this review also happen to be the most expensive.
Not all 633x cards are created equal. The two cards reviewed from Lexar and Transcend are both marked as 633x but vary in performance greatly.
4k video recording using action cams and drone cameras have a typical bitrate of 60mbps or 100mbps, corresponding to 7.5MB/s to 12.5MB/s. All cards in this review should theoretically be able to handle this usage easily.
Using microsd card as supplemental phone storage potentially could benefit from a faster card,

Best Looking Card (if it matters):
Sandisk Extreme Pro: Red/Gold with white print
Lexar 1000x: White/Gold with Black/White print
Samsung Pro+: White/Black with a red stripe and Black/White print
PNY Turbo: Lime Green/Black with Black/White print

Update 9/14/2015: Added additional cards to the list.
Update 9/18/2015: Added 128GB Sandisk Ultra and Lexar 633x
Update 9/21/2015: Added 2 PNY Elite Performance cards

Warning, you need a device that supports the physical UHS-II interface to get the full speed on this product. Most microSDXC slots are NOT UHS-II, many even relatively new devices are only UHS-1. I made the mistake of trying to use this with the 2016 version of the Intel Compute Stick and that device only supports UHS-1. The net result is that the write transfer times are significantly slower with the Lexar Pro 1000X device than they are with the more commonly available and often cheaper UHS-1 cards.

However, the USB3 adapter that comes with the Lexar Pro 1000X does provide pretty speedy performance, with reads around 150MB/s and writes between 70 and 80MB/s (measured with the CrystalDiskMark v5.1.2 utility). Contrast that to the what I got in the Compute Stick's UHS-I port, about 70 to 80MB/s on reads and only 25 to 50MB/s on writes (roughly one half of the speed that was produced with the USB3 adapter).

In any case, note that the speeds shown above are with a benchmarking utility, so in either case your day-to-day transfer times are likely to be even slower than what is indicated above.

Lesson learned, not all microSDXC UHS ports are the same when it comes to read/write speeds. Basically, if your device only supports UHS-I then you want to buy a UHS-I U3/Class10 device for the best possible performance (as of spring 2016).

The new Gopro 5 Black and Session 5 only writes at 60 Mb/s (megabits per second). This card can write 455.6 Mb/s (i.e. 56.95 MegaBytes per second). Plenty fast! This card blows all other cards out of the water because you can copy off of the card faster than any other card around. Think about it, you spend most of your time copying files <b>OFF</b> of the card to your computer. This card saves time!!

The fastest read on a 128 GB MicroSDXC card I have found
Lifetime Warranty on card, 1 year on reader
126 MB/s Read - 56.95 MB/s Write on my system, using CrystalDiskMark 5.1.2 (x64) on Win 7
Includes a fast USB 3.0 adapter
Fully recyclable packaging

Works on the following:
GoPro Hero 5 Session
Samsung Galaxy Tab S 10.5
Samsung Galaxy S3, S4, S5, S6, and S5
Samsung Note 4
Microsoft Surface Pro 3

Tested with:

ATTO v2.47
CrystalDiskMark 5.1.2 (x64)
h2testw v1.4

Runs absolutely perfectly in my Moto X Pure Edition phone, used as adoptable storage. When converting to adoptable storage I still got the warning that the card appeared to be too slow and may cause performance issues. Well, rest assured it does not. Not sure what would not get that warning as this is one of the fasted cards you can buy right now, especially at this price point. Kind of wish I had gotten the 64 GB version though for the extra space, and according to another reviewer it slightly faster too. But this is plenty fast as it is.