I think the trick would be to find out how many calories it actually has. My understanding is that it has at least 1 g carbohydrate per serving/packet, which means it has 1/4 the calories of sugar for the same sweetening power. You have to decide whether it's worth the difference in price. For me, it might be worth it if I were baking or making a dessert, but most days I just don't use that much sweetener. The difference between 16 calories for a teaspoon of sugar or 4 calories for a packet of this stuff won't make or break your weight loss program if you only use one serving a day in your coffee, but it might if you're eating a dessert every day.
As for safety, I can't find any info on how they make the monk fruit extract, but that's not a very large part of the sweetener, anyway. It's mostly erythritol, which is probably the safest of the low-calorie sweeteners. Unlike the other sugar alcohols, it doesn't cause tummy problems for most people. It does still make foods taste/feel cold, but the main drawback to erythritol has always been price. Erythritol is what I would use as my main sweetener if it were easier to find and less pricey.
In fact, I would check the price and consider just getting erythritol if it's not much more. The monk fruit extract probably isn't harmful, but it hasn't been tested and I'm sure it doesn't lower the price any, so why bother, when erythritol without it tastes good and has a long track record of safety?