There will be light spots. This is ok. Also, the silverskin will be breaking off so there will be a little flaky material in the pan too. There are however, beans which have had the silverskin removed. And, there will be smoke, so turn the vent fan on.
Taste purely depends on the type of beans and the degree of roast required.
Take beans off the burner and let cool in another pan. This method gives an even roast to the beans. Generally, a radiant heat oven is your standard in house oven which is heated by either electricity, gas or wood. Gas and wood heated ovens will catch the beans afire more often than electricity, but those ovens tend to be better built. The oven method tends to contain the smoke and chaff in the oven.