I am a Turk who learned Finnish as an adult. A striking similar between Turks and Finns is that both think their language is phonetic/read-as-written. While Finnish performs definitely better than Turkish in this aspect, both are far from being perfectly phonetic.

As the other comment mentioned Finnish isn't that phonetic at all. Even the simple "tervetuloa" is actually pronounced as "tÄrvetuloa".

But out of all languages I've learned/tried to learn, Finnish definitely is relatively more rule-abiding. And it has a huge bonus of being very obscure as to be used as a secret language :)