My son gave me this for Christmas, having picked it from my Amazon.com wish list.
Like all Victorinox Swiss Army knives, it's a brilliantly designed gentleman's multitool. I wanted the altimeter and thermometer features for my occasional travels to Colorado and motorcycle camping.
Since my home state of Indiana is pretty flat, especially the northern half where I live, the altimeter's chief value is as a barometer - if the altitude goes up, the pressure is dropping and stormy weather is coming, if the altitude goes down, the pressure is rising and good weather will follow.
Likewise, I haven't done any real outdoor stuff since Christmas, so about the only temperature readings I've seen have been straight out of my pants pocket, which I can report is a pretty consistent 84 degrees Fahrenheit.
I love gadgets and this is a cool little gadget.

First off. The knife is great. I wouldn't expect anything less from swiss army. only bad part about the knife is that the altimeter has an accuracy error margin of about 75%. And since this is both the title of the knife and the main feature of it, I give the knife a two. Only because you can get a knife just like it without the altimeter that works just as well.