Recently I purchased two shotgun mics, neither for music work, but I thought for kicks and grins I would run both and see what I thought.
First up is the Neumann KMR 82i, this is a long shotgun. I played with it with just voices and it does exactly what it is suppose to. Picks up the speaker it is pointed to with little bleed from peripheral sounds. If you have a need for a long shotgun for vocals, this seems to be a great option. I bought it used and even used it was pretty hefty on the price tag.
Next, I picked up a Rode NTG-1. This is a short shotgun which could be camera mounted if needed. I picked this up new off eBay for just under $200. I chose this mic after asking a few sound mixers I know about some short guns. They all agreed this was a pretty good mic. I have to agree with them so far. It does tend to pick up a bit more of the peripheral sounds, but from what I understand, most short guns do.
So, since I tried both for music and this is a music board (primarily), I thought I would give my thoughts on both when used for music. While the Neumann certain has the reputation over Rode, The sound quality for music (not voice only) is better on the Rode. This is a very unnatural bump in the mids when using the Neumann. Actually I suspect it's not so much a bump as the bottom end is not a pronounced and the top end is boosted a bit. These are mics designed for on-location sound, and not music, so it makes sense. The Rode has a much more natural sound when doing music. I would not hesitate putting the NTG-1 on a camera and just using that mic. You're not going to get world class sound, but it is leagues ahead of the built-in mic. However, beware. The NTG-1 does require phantom power, if your camera can't supply that, you're better off with the NTG-2, which can run off AA batteries. The NTG-1 & NTG-2 are suppose to be the same mic, one simply can run off AA's or with phantom, the other requires phantom all the time.
I can't slag Neumann, it really wasn't designed for what I was doing, and there are certainly times you need a long shotgun, but you have to be ready with additional support (it's nearly 15-in long) when you run it, and I wouldn't run this on a camera by itself unless it was voice only work.
Overall, I think the Rode NTG-1 can be used for music, but still shotgun mics have limited use in the music side of things. If the goal is to narrow the audio field to avoid peripheral noises, you're probably going to be better served by hyper-cardiods. However, if you want a simply solution for mounting on a camera and shooting video and audio at the same time, the NTG-1 or NTG-2 is certainly worth a look.
Wayne