Pronunciation is a separate issue, though. I'm assuming Overdriven wasn't simply talking about that, but general English skills, such as grammar. But yes, Russians do tend to have better pronunciation (what kind of a fucking word is that, anyway? Pronounce->pronunciation, makes no sense) than Italians and the Spanish.
Young well-educated Chinese and Japanese do often have surprisingly good English.
I was basing this mostly on speaking rather than writing seeing as I didn't do the teaching. I found the Russian kids to be quite shy but when they did speak they were very clear and comprehensible with few mistakes in their grammar.
Obviously these kids were from wealthier families as well (they had to fork out a lot for these summer schools) so I don't know the backgrounds to their schooling but it would likely have been of a higher standard.
I found the Spanish kids though to struggle quite a bit with speaking English. They could string sentences together but usually with fewer and less complex words.
At University the Chinese students always had excellent written skills. They could understand anything on paper at that level but they often found it difficult to communicate verbally and stumbled a lot over it.
All first hand experience though so nothing to base anything factual on.