Feature:
While a switch is generally considered a non-pro feature, in the semi-pro market, it's quite useful. Every potential source of feedback counts, and do you always trust the sound guy to turn your mic off between sets? Also since I sing primarily backup, and not on every song, I turn it off @ practice as well when I'm not singing. So this is a perfect mic for a gigging backup singer.

Value:
It's also not the cheapest mic out there; the SM58 still seems to be the most common vocal mic out there and I can't say for sure that this mic is $50 better.

Desirability:
Well, this category is a little silly for a mic, but yes, it's a nice conversation piece, since it's not the most common mic out there.

Sound:
More clear, less "warm" than the Shure Beta 58A, which is probably the most direct competitor in this price range (and also probably the most popular vocal mic in this price range). I prefer the Sennheiser, hands-down. I primarily sing harmony, and find the clarity of this mic allows me to deliver harmonies without crowding the frequency space of the lead vocals.

Ease of Use:
It's a microphone.

Feature:
You must have the on-off switch.

Quality:
Ive had the oldest mic five years, now. Sounds like it did when I bought it.

Sound:
I don't sing, I just bring the stuff. I have two of these mics (one for backup). Every singer that has used it tells me it is the best mic they've ever used. I probably have sold about six of them when I tell the singer where to buy them. I just bought a third one because it is such a good mic.

Ease of Use:
How hard is it to use a mic? Sing into the end without the cord.

Support:
Haven't needed support

Sound:
These mics are the best all round mics money can buy far better than any shure mic build quality is fantastic.