I would still buy a Samsung device without a doubt. I actually think the newer devices should be more extensively tested and far less likely to run into issues. I also agree with others that other phones have issues, even if less severe, that don't always get as much publicity.
One of my friends with an Apple Iphone (I think an Iphone 5, but it was only about 1 year old or less than that) had his depleting battery as soon as it went off the charger, basically going completely dead immediately. He said even when it was plugged into the charger it would not charge. He was actually in a car accident, and luckily someone stopped and let him use their phone to call for help but otherwise his phone had died. So there are other very inconveniencing issues that can occur with phones. I know a phone catching fire is a huge issue, but again I feel Samsung will be extra cautious in preventing this now. I think you should actually be more concerned if you own a current S7 or S7 Edge. I own an S7 but am not too worried about it catching fire. There was actually an article recently about an S7 or Edge catching fire in my state but I'm not sure if it was found to be legitimate or not.