Are asking with regard to first time use of a messenger application or about upgrading from the previous version of Messenger.
If you're asking about the first point you'll have to wait for someone that's more security smart to answer about hackers (although I'd have thought a good firewall would overcome that problem), but messengers are very effective ways to communicate. A cheap microphone and speakers turns messengers into free (except for the costs of internet conmnection) phone calls and files transmitted from one user to another. Try it and if you don't like it give up.
If you mean upgrading - I can't see any great advantage between Messenger live and the previous (MSN Messenger 7.5, I think) except the "Shared Folder" which means that anything you put in the folder is sent to all other online contacts - I'd say you might as well just send the files manually unless it's a workplace thing.