Last week i bought a cheap EOS adapter to try my Canon L lenses to see if it was worth getting an auto focus adapter, the cheap adapter has no aperture adjustment so these were probably shot wide open, i think i might get an auto focus adapter
I don't own the A7 but I have owned an A7R since Nov '13. Since I'm coming from a Canon background I have loads of both FD and EOS lenses. All work very well with both a Metabones III and King adapter. The King adapter is not quite as snug a fit as the Metabones but is one-third the cost; both allow automatic operation of EOS lenses. I also have various adapters for FD, Minolta, Pentax, M42 and T2 lens mounts; all manual but they also work reasonably well.
The A7/A7R is a great camera for legacy glass AND really does make a few of the old lenses shine! My old Pentax K (35mm film) lenses, in particular, yield great results. Better than I ever remember them performing with film...
You can also get adapters with built-in aperture adjustment for those automatic lenses that won't work with automatic adapters. There is also a very nice helical adapter for macro work with convention lenses; works wonderfully with a Canon 200 f/2.8 lens I own.
bwa