One of the design goals of the Newton was to make it so that the user wasn't at risk for losing data. The system has a backup lithium battery which should be able to maintain the contents of memory for many years. Losing the contents of memory when the main batteries go dead is unacceptable performance. In fact, I've run mine down *many* times, to the point where the Newton goes dead or won't start up, and never lost the data in memory. *It's not supposed to happen.* The battery going dead is not some weird anomaly, it's normal, everyday behavior. The system doesn't say that you might lose data when the battery gets low, it just says you should change them soon. If you've lost all your data because the main battery went dead, there is some problem with your Newton; maybe the backup battery isn't live or making proper contact; maybe there is a hardware or software problem. I'd talk to SOS-Apple and try to get it fixed.
If letting the battery go dead puts you at risk for losing all the data in your Newton, Apple didn't meet its design goals, and the Newton is certainly not friendly enough to be used by ordinary people, who make mistakes (like leaving it on overnight, letting it get cold, forgetting to carry spare batteries, don't have the opportunity to change the batteries right away, etc). Assuming that the result of a user error should rightly be all data loss is typical of poor design, not good design. If this were really the case, I'd say we all should return our Newtons immediately!