I've had good luck using this chip, particularly when I compare it to the AD595-AQ.

What I like:

• Handles amplification and ADC on the same chip. I don't need to worry about analog signal routing, or any of the complications of ADC accuracy on the µC.
• Really simple pinout, therefore a simple board layout.

What I don't like:

• The MAX6675 Arduino library isn't suitable for state-machine-based µC applications. I needed to write my own low-level SPI routines due to both timing and SPI compatibility issues.

ADC timing gotchas, :

• Be aware that since the ADC conversion starts upon taking CS high, it might be wildly out-of-date if, say, you're only reading the MAX6675 every minute or so. Toggling CS low, then high can get around this.
• If you take CS low during a conversion, it'll stop the conversion that's already in progress. I seem to recall it'll just return the previous value in this case. So, don't read faster than about 4Hz.

I've used this successfully in a project which uses:

• 5V supply
• ATMEGA328P-AU Microcontroller
• Other SPI peripherals on the same bus
• Maximum 4Hz read rate

Not sure if I just got a bad part or if there's a larger quality issue here, but I attempted to use one of these devices in an oven control with a standard type K thermocouple. Power was 3.3V.

The device worked perfectly for several hours including multiple power cycles for testing purposes. After those few hours (fortunately during a test cool-down cycle) suddenly the temperature readings went to zero, and on subsequent power cycle the chip literally exploded (!) destroying the attached ARM controller circuitry in the process (probably due to shorting out and applying either 0V or 3.3V at high current to the delicate SPI pins). I have no idea how this is possible besides a manufacturing defect; the 3.3V supply was rock stable throughout and the ARM device on the same supply didn't blink until this chip exploded.

I have been in electrical engineering/embedded systems for well over a decade so I know all about ESD precautions, etc. This is the first time I have had a non-Chinese sensor chip do anything like this!