I tried IDM recently but it did little to impress me.
Compared download speeds for specific files (every file was 3 gigabytes at least), compared them on downloading multiple files (~30 at once), saved some videos here and there, and overall there was no difference.
And lastly, note that I do not, and will not, use any download manager extensions in my browsers (I'm not referring to add-ons which are natively coded for browsers, rather the extensiosn that come with the installation of external standalone download managers), as they are very exploitable and thus they greatly increase risk of infection due to exploits. (not to mention potential stability/compatibility issues, as well as an increase in load times)
Call me old-fashioned, but in my opinion, downloading files with download managers should be done by copy-pasting their links only, and not using funky on-the-fly linkgrabbing techniques from within browsers.