I liked the app enough in the free version that I signed up for a year of premium. (Note: starting in December 2018 the yearly price for new premium users will rise from $29 to $36, the first price increase in several years.)
I'm still trying to wrap my head around the best ways to implement projects, labels (tags), colors and filters (smart searches).
Because it's so flexible it can be customized many ways and therefore get complicated. When I started I had a SHOPPING project, then I applied tags for Home, Work, Pharmacy, etc. But then I deleted the SHOPPING project and just put everything into their primary projects and added a 'shopping' label to items I wanted to buy. Six of one, half dozen of the other, right? Anyway, it seems to work a little better for me. But it still can get confusing.
There are reminders, and also due-dates, and both can give you alerts. So that's more possibility for confusion. But I mostly blame myself for the confusion, not the app.
One really nice thing, even for free users, is 2-way sync with google Calendar. So you can schedule things in Todoist, they'll appear in your calendar, and if you change the info or date in the calendar the changes will sync back to Todoist!
ALSO: Todoist announced that in late 2018/early 2019 they're actually revamping the app significantly, and no one knows yet what exactly that means.