It can turn out some of the skeletons in the cupboards as well, so just be careful which path you follow and what you learn, it may not be what you want to see or hear.
My cousin has been tracing our family tree, but it depends which branch he follows as to the results he got, many leads got to dead ends or wrong ends and he had to go back and start again.
Local records offices, local church grave yards do turn up useful leads with Marriages, christenings and death records.
I dabbled a few years back trying to find out more about one of my uncles who had a wife and daughter killed in the blitz, but one of the problems with such incidents was that records offices were also destroyed and I came to a dead end...But another surname the same as mine and my uncles threw out some interesting information on another Mother and daughter who were killed when a Me109 was shot down by a Spitfire and the plane crashed into their farm yard on the last day of the Battle of Britain in September 1940.
Good luck with any research you do.
If there are any relatives killed on military duty during the numerous conflicts the War graves commission has a huge data base worth looking at.