means it's an old and well-used tool. That is, the tool has worked sufficiently for a long time at least for this man, but this phrase does not directly say it's a high-quality tool in a general sense. For example, even a very cheap hammer can be if someone used it for a long time.
**EDIT** : To clarify, when modifies a person or an action, it tends to have a positive connotation similar to /. But when modifies an inanimate object, I think it just refers to something that has been used for a long time and is showing its age, but is still perfectly usable. Depending on the context, it may have a value as a vintage, though. See this thesaurus entry, too.