auto: useful, annoying or bad practice?

[Gerald]

I'll freely admit I haven't put a ton of thought into this post 
(never a good start), however I'm genuinely curious what people's 
feeling are with regards to the auto keyword.

Speaking for myself, I dislike the auto keyword. Some of this is 
because I have a preference for static languages and I find auto 
adds ambiguity with little benefit. Additionally, I find it 
annoying that the phobos documentation relies heavily on auto 
obscuring return types and making it a bit more difficult to 
follow what is happening which gives me a bad taste for it.

Having said, the thing that really started my thinking about this 
was this post I made:

https://forum.dlang.org/thread/fytefnejxqdgotjkprpo@forum.dlang.org

Where in order to declare a public variable for the RedBlackTree 
lowerBound/upperBound methods I had to fall back on using the 
ReturnType template to declare a variable. Jonathan was nice 
enough to point me in the right direction and maybe there's a way 
to do this without having to fall back on ReturnType. However 
this made be wonder if reliance on auto could discourage API 
writers from having sane return types.

So I'm curious, what's the consensus on auto?