If you have a working system you might want to hold off on the upgrade to 8.10,
at least for several weeks. First off downloads are slow because the servers are
busy. Secondly, there are inevitable problems with upgrades. Although all of the
bugs should have been detected and fixed there are inevitable kinks that need
time to be worked out. Finally, you have to ask yourself if it is worth the
risk. It is a tradeoff. You are getting the latest and greatest, but you risk
not having everything working the way you want. It is hard to better a system
that is working well. In the worst case scenario you may have to install more
than once. In this case, it is advisable to download the ISO and start fresh so
that you always have the CD or ISO at your disposal instead of opting for an
upgrade.

I have had upgrades go awry. For example a power outage can happen or servers
can go down and you can have a partially upgraded system in which neither works.
Remember to back up all data before upgrading or re-installing. If possible keep
your home folder on a separate partition which you NEVER format, that way you
can re-use your home folder. This makes the upgrade and re-installation a
cakewalk. The trick is to do a manual installation and choose your own mount
points instead of selecting the defaults.