The fire is really not for someone that has a huge current library they want to consume. It is to consume stuff on the Amazon Cloud.
The "I don't like cloud" is becoming a minority opinion. Everything is moving to the cloud. Lion basically keeps most all of your stuff on the cloud. It is available on all your devices and automatically backed up on Apples cloud.
Android phones are tied to the google cloud. I have google plus and any photo I take on my phone is automatically added to my G+ account.
Sure, it might take time to upload your content to the cloud, but once it is there you can consume it on your fire and probably other devices coming down the pike.