We have used previous versions of ArcServe (6.5), and are currently using BrightStor Enterprise Backup with a tape library.
In my opinion BrightStor needs about as much attention as ArcServe. For example, a backup job may work fine for many days, then it gets file access errors (status Incomplete). After applying a filter, it runs again for a while. Library handling is not fully automatic, especially inventory. Error messages do not always reflect the cause of a problem, only that there is something wrong. We have discovered several bugs. As in ArcServe, client agents occasionally stop responding; restarting the client service brings it back. The internal security and backup domain concepts need improvement and/or utilities.
BrightStor is much easier to install and setup than some competing products, and the menus are easy to use. Documentation does not always match the software, and could use more detail.
Some of the problems reported in these forums under ArcServe also apply to BrightStor (the same is true for CA support sites). These forums (which I only found a few weeks ago!) have been very useful in diagnosing and correcting problems.
After working with other (more expensive) products that require virtually no attention after installation / configuration, other than monitoring status, this product is somewhat disappointing.