Older mysql client with newer server compatibility

[Honza Horak]

Hi experts,

I'm thinking about compatibility issues between older mysql client (say 
5.0.x or 5.1.x) with newer mysql server (5.5.x or 5.6.x). After some 
tests I've noticed no issues and it seems to work just fine. Is anybody 
aware of some problems that I can expect?

Cheers,
Honza