In Russian, unstressed vowels are reduced so they are pronounced ambiguously. And when you try to write them down, you need to choose the correct letter for the full-length vowel. There are also double consonants that often are not pronounced differently.

On the other hand, if you just sound out the words syllable by syllable with full-length vowels, they will be completely understandable. You'll just sound a bit over-formal and/or robotic.

There were several attempts at spelling reforms, but only the first one (in 1917) stuck.