[vp8989]

MySQL stored procedures work fine when invoked from application code IME. The lack of native collection types is not ideal when you need to inject N values to a bit of data logic. As such, and for other reasons, I personally prefer raw parameterized SQL passed through a lightweight ORM that handles mapping for me as well as securely marshal a collection value into a parameterized query. But beyond that Id say that they are "usable".

Can you elaborate on the challenges you've faced with them?

[zzzeek]

for MySQL? only that they do not seem to be commonly used at all, within the already small set of modern applications that scale out on stored procedures successfully. MySQL's base of maturity is the PHP application that is using straight SQL.

I'm not an SP guy so while an SP app using a platform with lots and lots of widespread use and maturity for that style of programming, like Oracle or SQL SQL Server is already unpleasant for me but at least I'd know I was on well-trod ground, doing it for MySQL where issues I hit would have very little precedent / workarounds / community I'd not want to get involved with for anything important.

[vp8989]

Fair enough. To reiterate, Im personally not a fan but I would say they are generally usable.