I got this question recently in my Drift bot, asking me what I think of slot filling at present.
Since I wrote the article, the underlying implementation hasn't really changed. But I have written more about this and also created a video course.
So here are some resources which explain how I feel about slot filling the concept vs slot filling the feature:
Here are four questions you can ask yourself to decide:
1 Do you want to build multi-turn conversation dialogs which are also flexible?
2 Would you like to actually understand what is going on under the hood in your bot?
3 Would you prefer a bot which is more maintainable over the long run?
4 Do you have the time/money/dev resources to understand how contexts work so you can build a bot which works the way you have designed it?
If you answered Yes to any of these questions, I suggest you don't use the slot filling feature.
Check out my guide to Dialogflow slot filling.