User blog comment:Bleeh/Error: Glitchy Sims with OS X Lion (Mac)/@comment-198.228.198.214-20111118182202/@comment-98.221.208.144-20111219172906

I'm not talking about keeping backups all the time, but you should always run a full backup before doing a major system upgrade. That's just good practice. Aside from that, Time Machine runs in the background, so it is actually very convenient because you don't have to do anything beyond the initial set-up