I have dropped them a couple times and they still work fine, so they are built pretty sturdy. They sound a bit on the bright side, but also provide a nice full low end. I have on many occasions preffered the sound of a pair of these on acoustic guitar over some high-end large diaphragm condensers. They achieve what they're supposed to, and then some. I regularly use them as overhead drum mics, but I've also used them on snare, electric guitar, upright and grand piano, and even vocals. The NT5 is a very versatile mic.
Reliable? Absolutely. I've never run into any problems with these mics. The only problem I could foresee would be preferring the sound of a different mic over these, but that will always happen and is not really a problem.
I absolutely without question would recommend the NT5s to others. I have and will continue to do so. Not only would I buy them again, I WILL buy them again because I want to have more of them for their many different uses. Every studio should have at least ONE set of these, even if they already have Neumanns and AKGs and whatnot.