When i was doing it for the first time i was also worried about it so much. I googled hard. I found that only 2% of the careless people who are doing it for the first time get their phone bricked. Bricked phone means the phone is now as useful as just a brick ( It does not boot at all) . I did it for the first time safely, no issues were faced. However if the phone is switching on but not booting completely, it can surely be corrected. So in my opinion it is safe and worth doing. Don't do it only if you don't like geeking around and you are so damn careless. :) happy rooting.