To be fair, the standard libraries do have some unexpected inconsistencies. The array module indexing at 0, whereas everything else starts at 1, setelement being (index, record, value), but the similar feeling dict/orddict:store being (key, value, dict) (so the value and the collection items are switched between the two), things like that. Nothing really major, but a few things that mean you end up looking at the docs or autocomplete now and again because you forget argument ordering.

Erlang strings are quite inefficient if you aren't careful, and their printing is just terrible; a lot of the Erlang community uses binaries where possible instead, since those behave more like you would expect and are generally faster (especially since concatenation can be achieved with io_lists). It's a fair point; most people trying Erlang assume strings are a basic data type (since they were in whatever language they're coming from), they don't know to use binaries instead wherever possible, and so as soon as they see how slow they are, or when they get a non-printable character in it and the entire string prints as a list of integers, it's rather offputting.