Namespaces rock. Chained with the spl_autoload method, you can then import with a simple:
use PathToMyPackage AS Package
Aside from that, I've noticed no instability issues. I've also not noticed any substantial upgrades in the OO environment, though one bug I've seen in an is_interface reporting has been corrected in PHP5.3.0.
What I have noticed is that reflection is more of a pain now. ReflectionClass expects a fully qualified name, so with namespaces you need to know what the namespace is in order to import it o.O. That I do not like, since it will not take out of current scope context - so if you have:
use \Path\to\Package AS Package;
, you cannot just do
For you're dev box, definitely PHP5.3.0. If you do not have a supporting server, avoid the namespacing.