Summary: I purchased the 1.5TB version in the spring of 2009 for use with my 24" iMac 9,1. Maybe I've just been lucky but I have been using it constantly for Time Machine backups and other small storage for almost two years. It has performed flawlessly. The only 'problem' I have with it is that it tends to spin down too quickly. Many apps will enumerate drives on startup and they will 'hang' until the drive spins up. It is only three or four seconds but it is annoying.
Summary: Simple plug and play setup, fast and quiet. I transferred 40 gigs of info from my old drive in probably twenty minutes with the Seagate plugged into the Firewire port and the old drive in USB. The manual is breathtaking in its brevity, so you have to search the Seagate site for more info. Only a couple of caveats. I bought this drive because I was having mounting/unmounting problems with my old external drive.
Summary: I bought the 1TB FreeAgent for Mac about a month ago. I don't think I've had it long enough to rate the reliability, but installation was a piece of cake. I think it took longer to decide which of the three included cables to use, than to actually plug it in and wait for my Mac to recognize it. I think the way it lights up when active is cool. The transfer speed is seamless - I'm using the included Firewire cable and it is connected to my Mini Mac.
Summary: I got this drive on sale and immediately put about 500GB of data on it, without any issues. It compares to my previous 500GB FreeAgent Pro in terms of speed, though I've only used USB. The included backup software is okay-ish, but I prefer to use my own software. You can opt out of installing the Seagate Manager by just moving the installation files to a different folder on your drive.
Summary: My computer consultant recommended this product to safeguard my personal information in case of computer failure -- it's nice to know my new information is automatically stored on a daily basis -- if my computer crashes I have up-to-date backup. I assume it is working well -- it has not yet been tested.
Summary: I purchased this product after extensive research and after my former external hard drive died. It could not be easier to set up/ install. Mac users -- be sure to look for/ purchase the MAC version of the product -- using it with Time Machine is effortless. I am very happy with the product.