Don’t trust the Japanese!
…well, at least not when it comes your Japanese language ability.
From my experience, almost every Japanese person that you meet will say the same thing, “sugoi, nihongo ga jozu desu ne!?” (Wow, your Japanese is really good!). You will blush, and smile, and think to yourself “wow, those Japanese lessons really paid off.” But in reality your Japanese sucks and your still at a 1st grader’s level.
Japanese people will say the same thing to anyone who can simply say “arigatou, onegaishimasu” or can count to ten.
Partly it’s because they’re being polite. Partly it’s because most Japanese people think of their country as a small island, and the only place on earth where Japanese is spoken. If they see/hear a foreigner speaking their language they are really surprised. They’re usually amazed to encounter any gaijin who wants to learn their language.
So if you encounter this reaction, don’t let it get to your head and think “wow, my Japanese is great, I don’t even need to study.” Keep studying and working hard! Mastering the language is a lifetime endeavor. Even if you study everyday for 5 years you will still not be as fluent as a native speaker, but if you stick to it you can get pretty darn close.
Gambatte ne!