I use it for all manner of searches. Knowing how to tune a search appropriately helps. Tossing in an additional keyword, or a set of associations can help:

    (phrase one| phrase two|phrase three) 

Using bang syntax is also quite useful.

In my experience, where a DDG search doesn't turn up good results, an SP or Google search (both bang-searchable) are generally not much better. I'll revise my terms at that point.

Again, date-range is the notable exception, and it's not a minor issue.