I've been playing around with CrashPlan now for about 2 weeks. If you're thinking of changing your backup strategy, I really suggest you try the application and the 1 month trial of the cloud backup.
So far I really like it. The client continuously runs, and on my computer requires about 140 MB of RAM (!). It continuously monitors changes, and uploads changes on the fly. You can backup to the cloud (CrashPlan Central). The application is free, and it allows you to backup to friends, and across your LAN for free.
I have it set to backup about 200 GB of data, which required a long time to backup to the Cloud as it only uploaded at 1.5 Mbit/s. You can limit both WAN and LAN up- and down-speeds based on whether you are at your computer or away, but my upload speed maxed at 1.5 Mbit/s (probably limited by my ISP). Download speed is much better - I did a test restore that ran around 2.2 MB/s. Restoring from a local drive (a USB3 drive in my case) is basically at the speed of the drive, although backing up, at least the first time, seemed relatively slow as well. It does compress stuff, and with a mix of mostly videos and some other random stuff, it got ~25% compression, but the downside is you need the application to open your backup. You can have it backup older versions, although I have not explored the versioning system. You can restore using the webpage, but you're limited to files <200 MB in size. They'll also ship you a HD to seed your upload or to send you your files, but I'm not sure how expensive that is.
There is an iPhone application, and it works pretty well. I've used it a few times to download documents I've recently worked on, and it was slick. Some have privacy concerns about the iPhone app, but I don't really care. Seems to function similar to DropBox.
All this, including unlimited single PC backup for $3/month is pretty good if you ask me. I have about a week left on my trial, and I'm really tempted to buy a year or two's service. Especially now with the Thailand devastation. But my big hangup is that to do a restore of my 200 GB would require 27 hours (at 2.2 MBps=16.7 Mbps if I did the math correct). I guess it's not that bad.