Import Quicken Data Files
Although the documentation claims GnuCash can import QFX and / or QIF files, it cannot. I exported one Quicken account file (a brokerage firm account file containing stocks, cash "category" / "account" mutual funds and annuities. For the QFX import, a blank "Generic Import transaction matcher" window appears. Clicking the "OK" button does nothing. Clicking the close window gadget closes the window but nothing appears in the main window. No new account.
For QIF, paging through numerous panes makes it look like the import is happening until the final "QIF Import" pane after the "Book" options panel selections are made. Multiple alerts, "A bug was detected converting the QIF data" appear. After the last one ("A bug was detected while detecting duplicates.") is closed SOME of the holdings in the account appear, others do not.
Also, it appears that prices for securities need to be manually input as they were not imported (imported "accounts" show values of $0) and I find no way to get an online price update. So there appears no way to track profit-loss / capital gains for tax purposes without manually setting up "Lots" and entering 30 yrs of price, stock split, and dividend re-investment info making the whole point of the program kinda useless.
Finally, it appears to have no way to deal with annuity contracts held in "Trading" accounts whether imported or not.
Without adding / fixing all the above, GnuCash is basically a waste of time and certainly not a Quicken replacement (as aged and flawed as it has become due to lack of competition).