What do you want it to do?
I was looking for a device that would give me the minimum temperature - so I can know how cold it got overnight ... while I am camping.
I looked at the Kestrel devices first, but couldn't find any indication that those provide minimum/maximum temperature, so I looked elsewhere.
I ended up buying a Brunton ADC Wind, which captures hourly temperatures for the last 24 hours - just what I wanted. It also provides wind speed and related info, though I haven't a clue how accurately it records it.
Overall the ADC Wind is OK. Its interface is not the most obvious. I wish it provided a little more "in-device" guidance for someone who isn't a frequent user.
I also wish the ADC Wind had come in some kind of case. It turned out that the nylon sack my Rittergrip came in exactly fits the ADC Wind. Sweet!