Product review (5 stars): Preliminary review
I just bought this yesterday so this review is more of along the lines of my first impression.

Like other reviewers I tested both the indoor and outdoor sensors side by side and the temps matched, while the humidity was only 1 point off.  The temps also agreed with my thermostat when placed side by side.  I mounted the outdoor sensor on my front porch under the overhang last night and this morning the indoor temp matched my thermostat and the outdoor temp matched within 1 degree the weather reported by "Weather Underground" and "The Weather Channel".  BTW, both weather forecasters I mentioned reported different temps, but were fairly close. The humidity was in right in the middle of the two different values given by both of the weather forecasters I mentioned, so I have to assume that it is valid.

The bottom line is that this unit has passed initial tests.

As for longevity issues, I will report back if anything changes.

As for appearance, in my opinion, it is a very attractive device.  It looks better at home than it does at the store or online. The readout is large and easy to see and shows me the information I need to know. I wish it had a back light.

The reason I wanted a device of this sort is that I use a whole house fan and knowing when to use it is important to me.  The indoor and outdoor humidity levels are very important when deciding to turn the fan on or off.  The temp goes without saying.  For instance, right now the temps inside are nice but if I wanted to turn the fan on, I have an indoor humidity level of 49% and an outdoor humidity level of 76%, so I probably wouldn't use the fan.  Even if the indoor and outdoor temp is the same and assuming the outdoor humidity is lower, it can be beneficial to bring the outdoor air in to lower humidity to lower the heat index.  Well, I'm sure you get the idea. The point is that knowing these values has practical applications.

Of course , I may be preaching the the choir here.