My success with Back To My Mac was "spotty" at best until I started using the DynDNS service, port forwarding, and DHCP Reservations to get 100% reliable screen sharing sessions between my home and work computers. (It's not nearly as complicated as it sounds. Most of it is just one-time configuration which will then make things easier every time you do it in the future.) This does not require a subscription to MobileMe or involve any cost.
DynDNS hosts don't appear in the Finder like Back To My Mac hosts do, which is where ScreenSharingMenulet comes in. Click on the menu bar icon, type in the DynDNS hostname (check the box to "Add to My Computers"), and voilà! You're connected as easily as you always thought Back To My Mac would be, but never was.
ScreenSharingMenulet has just released a new version 2.0 which has preferences to show/hide Back to My Mac Hosts and show/hide local IP addresses. It also fixes a few bugs. One change that people may not like as much is the removal of the "Recent Hosts" submenu, but frequently contacted hosts can easily be added to the "My Computers" menu by checking a box when initiating the connection. A few other minor changes were also made.
Even if Back To My Mac worked consistently and reliably, I would still prefer ScreenSharingMenulet for initiating the connection because it's easier and faster to reach from my menu bar than going through Finder.