Use until it’s free! I do not believe that since Oracle bought the SUN the future of free MySQL will last longer than 2-3 years. Capitalism is capitalism. But until we got it we use it.
First of all – it’s free, so you cannot demand any support from Oracle. Many bugs, you have to deal with it, I will try to explain the bugs I faced. Please note that there are events which described in manual and what happened in real world are two different thing. Remember, if it’s a bug in the new version, developer will keep a silence almost forever. In that case you have no choice but to install older package of MySQL.