Personally, I dislike it. It just doesn't seem like it is worth what you pay. Here is what I think about their features list:
- Antivirus, antispyware, and firewall - Avira, MalwareBytes Anti-Malware and Zonealarm, all free.
- Wireless networking security - If you have Vista, this is built in.
- Online identity theft protection - SiteHound or Siteadvisor are both free for this.
- Performance tune-ups - Run disk cleanup and disk defrag both built into windows.
- Always up-to-date threat protection and system upgrades - All the programs listed are constantly updated.
- Protection without sacrificing speed - Any program will take memory, including this one.
- Simple, automated, and easy to use - So are the other programs.
- Manage all your covered PCs from a central hub - Can't beat this one... but is it really needed?
- One-click printer sharing - This could be a plus but not for $50 in my opinion.

- File and photo backup - Burn backups to a CD every now and then...
- Simple, automated, and easy to use - Make a task in windows for it to make a backup, theres your automation.
- Free support and help - Why would you need this when you have PCHF?

All features taken from here:
Windows Live OneCare - Home
Regards,
Adam