The old one allows you have to access to far more content from the couch (via purchases, rather than rentals)...just about everything you'd want to watch is there (a far cry on the new ATV), but you might have to buy it.
If you have poor wifi in your house or poor internet speeds, the old ATV allows you to sync (copy that content locally to the ATV)...therefor, if you sync, you know your show or movie will not stutter and will not be interrupted...
...then use the new ATV for netflix (if you don't already have it elsewhere) or renting the sparse amount of shows you might be able to find that you would otherwise have to purchase on the old ATV.
