Messages for mac is amazing. I will be having a full review up tomorrow. However it is in beta for a reason, so when Apple is ready to release Mountain Lion there will only be a few bugs rather than a lot of them. So what happens when the beta period is over? Well according to this that consomac.fr was able to find you will have to either get rid of it or upgrade to Mountain Lion. So there you go I will have an app review and the messages review up tomorrow.
uApps 