I have no issues with 3.8 so far, but if your not even familiar with the upgrade process I would not suggest the upgrade to 3.8 yet. Plus as ggace says there isn't much to rant and rave about. In fact the only thing i find useful is the fact that a quick reply for pms has been added but Princeton @ vb.org has made a great hack that will provide a pm quick reply as well. 3.8 on vbulletin.com - vBulletin Community Forum will lst all the new features and improvements.
I highly suggest you back up your board ecspecially if you have never done an upgrade/downgrade before. It's worth the extra 2 minute wait if you mess something up.
yup and if your not familiar with backing up use mysqldumper is (at least for me) the easiest way to backup and restore databases, and is necessary because, let's say you upgraded and you fpunded that a lot of your mods stoped working for that or that your skin don't show everything so you want to restore your forum to the older version now if you didn't backup xD well...you will have a big headeache and a log wait for the gold version