Backup to CD shares a lot of problems that backup to DVD has, with some interesting differences.
The main difference is that CDs ware 1/5th the size of DVDs, so you can't backup as much data. Consequently, the backup is "faster" because the data set is smaller.
So, CDs are basically not good for backing up your system, but, are a great way to make archival snapshots of your work-in-progress.
For example, if you wanted to retain 7 days of your past work, you can purchase 7 CD-RWs, and label them "Monday", "Tuesday", "Wednesday" and so forth. Put them in jewel cases, and then into a CD box.
Each day, either at the start or end of a day, run a backup of your work, and then store it. It won't take more than 10 minutes.
For your effort, you are rewarded with an archive of your most important data, at your fingertips.