The weakpoint, for me, of JWM is this scenario:
You have browser minimised, so appears in bottom panel only.
You have an html file in your open filemanager that you wish to open in that browser.
If this was openbox then dragging that html file down to the bottom panel browser 'tab' would automatically open the browser window again allowing you to drop the file there and see it immediately.
In JWM, that doesn't work, so first you have to click JWM open (but that alas obscures your file manager that has the html file open in it, so you have to click filemanager into the foreground (and hope it is not scaled to full screen) and only then can you drag and drop the html file into the visible open browser window.
Otherwise JWM is pretty great. However... because I use drag/drop files technique all the time I much prefer having openbox as my window manager.
Yes, clicking on the html file will all going well open it in the browser (if set up to work that way), but what if I want to use a different minimised browser or open it in a minimised text editor instead. A small advantage of openbox, perhaps, but in practice I really find JWM painful because it doesn't have that drag/drop capability. No big deal I suppose, but enough for my electing to use openbox instead (why suffer even in a minor way when I don't need to?). Configuring openbox (via the many tools available to do so) is also less painful to me than mucking around with JWM awkward-syntax text files (despite me having previously used JWM for years, and being very familiar with 'awkward syntax' config files more generally). The RAM saving of using JWM simply isn't significant enough for me to install it rather than openbox (except, maybe, on a particularly low RAM machine of which there are fewer and fewer still existing or working - I do have one ancient old machine, but not low-powered enough that JWM offers any improvement over using openbox/tint2 (for example) and anyway, such old machines often guzzle too much electricity compared to their utility and have clunky keyboards and are falling to bits (in the case of the ones I have) - just not comfortable to use (and I have a dozen other better laptops lying around gathering dust anyway). Puppy should move on from JWM machines (choice is okay though) and to some extent it has (with LXDE pups, for example). JWM certainly has its place though when target is truly old low-powered machine where every byte of RAM is important and every WM action that uses as little CPU cycles as possible (Hence I like WeeDog_Void32 that rockedge is developing - though for other slightly more powerful laptops personally I would modify its build plugin to use openbox instead).