Not that many years ago, you would not find a requirement of having experience with X-Ways to apply for a DFIR job. But now, some jobs recommend it and yet some others require it. This is not to say the other big players (Encase, Accessdata, etc..) are not needed or useful, just that XWF has made it to the same level at a price point that will probably not be beat with capabilities that still outpace other tools.
So......it makes sense to know a little about the tool that might put you over the edge for that next job. Of course, you need to be competent too, but like I've said before, "beware the examiners that use X-Ways Forensics because they probably know what they are doing."
For the future XWF users, check out www.x-ways.net for some details, download and read a quick guide, and when you move forward with XWF, buy the book :)