Spot metering is just a camera feature that measures the exposure from a single point. However, it is often misunderstood, and utilizing spot metering correctly may widen your technical capabilities when shooting in manual mode. Whether you are shooting in automatic or manual mode, cameras always measure the reflected light and tries to give you the correct exposure. Different metering modes have their own area of use; therefore, it is hard to say that one mode is better than the other. However, you should choose your exposure metering mode carefully, as cameras tend to give underexposed or overexposed readings in certain scenarios.
Spot metering measures the light from a very small portion, usually less than 5% of the total image area. This provides an advantage in scenes where the subject is either brighter or darker than its surrounding. Even this mode seems quite straight forward, it still requires practice and correct use of exposure compensation for achieving accurate results.
In this 15 minute video, nature photographer Steve Perry explains spot metering in detail and demonstrates how he achieves accurate exposures each time. He also explains when to use and when not to use spot metering, by sharing examples from wildlife photography scenarios.
Spot metering and using the Zone System are the most useful things I've learned so far in photography. A lot of people don't learn it anymore because they think that it doesn't apply to digital photography and while some of the particular parts don't (pushing/pulling film and such), I'd say that the lessons learned in regard to how to more accurately expose a scene the way you envision it in your head and understanding how to make sure you're capturing the dynamic range of a scene (without multiple exposures) absolutely do transfer over. Even though I have a MILC now and can benefit from live exposure, I still find myself relying on spot metering when practical.
Great tips. EVF and back LCD (live view) shooting definitely take a lot of guesswork out of figuring out exposure since you're essentially getting WYSIWYG.
I use spot metering a lot. I think it might depend on your subject.