I use the dumper all the time, probably nearly every day at work. It's super-useful and simple to use. That doesn't mean I don't use the debugger. I break the debugger out about once a week, maybe more. Sometimes I use it as a REPL by invoking it with perl -de0 and sometimes I use it to actually debug a program. (The former is more common.) Like most debuggers, it's a little weird and takes a while to get used to using. It's an extremely useful tool, though, and you should know how to use it. There are currently two books on the debugger. ISBN 0596005032 is a decent little quick reference. I haven't gotten my review copy of ISBN 1590594541 yet, but I expect good things.
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