Talking in Japanese is more than just “speaking” the language. It’s about etiquette of who you are talking to as well as gender form. European languages have gender forms, and to some degree etiquette. Japanese takes this to the extreme so much so that business speak is called keigo.
I do not like speaking Japanese until I get familiar with a person. Japanese people tend to be more critical of other Japanese people when it comes to making sure that they know etiquette and such; I often worry about making a mistake since I was born in Japan and raised in America. I had female teachers and not many people speaking the masculine form of Japanese, that I often was teased by my brothers as being effeminate. ( http://en.wikipedia.org/wiki/Gender_differences_in_spoken_Japanese )
Getting honorifics ( http://en.wikipedia.org/wiki/Japanese_honorifics ) is the easy part. Getting the honorifics in speach ( http://en.wikipedia.org/wiki/Honorific_speech_in_Japanese ) right is the hard part. There’s even a separate form of keigo for part time workers ( http://en.wikipedia.org/wiki/Manual_keigo )
Other specific example is saying yes in Japanese, does not necessarily mean yes; it has to do with the context… and saying yes, is usually more of a “yes, you are correct…” ( http://en.wikipedia.org/wiki/Yes_and_no see part about Japanese ) [This is also why yes/no questions are avoided in software that localize to Japanese… It’s an ok or cancel buttons]
There definitely are differences in communication patterns as well as culture. Otherwise there wouldn’t be books on the topic [http://books.google.com/books?id=H47dpXaMO_4C&pg=PA120&lpg=PA120&dq=Japanese+other+person%27s+point+of+view&source=bl&ots=PU0KbBs650&sig=YY2hC7URaeAUnfMTXR7kcSD3nyM&hl=en&sa=X&ei=jk8bT5nsJamZiALnrpzRCA&sqi=2&ved=0CFwQ6AEwCA#v=onepage&q=Japanese%20other%20person%27s%20point%20of%20view&f=false ]. This of course also doesn’t even go into dialects and slang/idioms [http://en.wikipedia.org/wiki/Japanese_language#Dialects ] It’s a lot more complicated to speak Japanese than you would think.
So with that in mind, I “speak” Japanese to my parents and relatives (other than my brothers). I can get my ideas across in Japanese, but I do not speak proper Japanese. At times it may be as bad as http://www.engrish.com/… heh.