0. Yes. But also I use various text editors, mind maps, Google Spreadsheets as checklists + categorization + comments etc.
1. It stores some information, and presents it in structured way, but I wouldn’t say that it is very helpful.
2. А) It is pretty rigid. B) Interface is a bit outdated and somewhat slow C) The more information you put there, the more inconvenient and less responsive it becomes structure becomes hard to browse (and you have problems filtering that), search may fail.
3. I’d say that charts or complex reportts are less important, and requirements don’t have to be put there. Important:
to be more or less responsive; do not depend on IE/Edge/other Microsoft products (sorry, but they are not the fastest); ability to structure and categorize information ; hyperlinks can be put in information fields, basic formatting can be put too.
4. For me most important is ease of work with information in hypothetical information management system. It does not have to be test cases, but something very flexible. “You want test case? Here you go. You want checklist? Here you go. You want to sort them by folders / tags? You want some description and notes? Here you go. You want to see only subset of data? We have extensive filtering.”
And don’t forget about response time. Users don’t fall in love with unresponsive systems, but they praise software which responds quickly.