I wouldn't say journaling could ever replace talking to someone, but I do find it very helpful. I journal when I'm starting to feel anxious about something. I find by putting my thoughts down on paper I'm able to take a more objective look at them. A lot of times I realize that my anxious thoughts are a bit extreme and really not true. I also find that it is great for remembering certain thoughts or events that I want to discuss with my therapist.