But it seems that my efforts went into a false direction. Everywhere i can read that neither perl nor C++ is suitable for real oop. Even with Java one isn't sure if that is. "The one and only genuine oop-language is smalltalk".

Smalltalk / Java / Perl / C++ all have different approaches to OO. I wouldn't say that Smalltalk is the One True Way - but it certainly concentrates on an OO approach that, to some extent, doesn't match the C++/Java view of OO.

is it worth making the effort to learn smalltalk

Yes.

and does it bring benefits to the practical daily work

Yes.

Then again, my view on the question "Should I learn language X?" is nearly always "yes". Learning more languages is a good thing. It helps you separate out language-specific features from more general concepts and helps you find the right tool for the right job.

Smalltalk is a fun language, and an influential one. Worth learning in my opinion. It's also very easy to get into since we have the free Squeak Smalltalk-80 implementation to play with.

I'd also recommend Kent Beck's Smalltalk Best Practice Patterns as reading material. Not a tutorial, but tons of fascinating nuggets.