I've collected a few Nikons. I have an F4, F5, and FM3a. (I have a few digi-Nikons as well...) Don't listen to the naysayers. Every one of these cameras is fun in its own way. Regarding the F5, I love that it can rip through a roll of film so fast! It shoots faster than my fastest digi-Nikon (D800). It's heavier, yes - but hey, that's also stability. I like to use it with my massive 200mm f2.8 cannon of a cast iron lens. It doesn't get much heavier than that. I added the MF-28, an absurdly over the top bit of additional capability.
Of course I don't need it. I don't need most of the stuff I own. That's irrelevant. It's an F5, man! It's the pinnacle of pro 35mm film cameras! There are plenty of nice, pristine, amateur-owned F5's around. No need to get an old beater.
The only annoyance to me is the AF-ON button. I'm addicted to AF-ON with my modern DSLRs, but on the F5 the button is just a bit too small. It takes conscious effort to activate it. On newer Nikons, the button is larger and easier to press. With the F5, I usually resort to using my thumbnail, rather than the meat of my thumb to press it.
(If you don't program your more modern cameras to disable auto-focus on the shutter and move it exclusively to the AF-ON button, give it a try. For many it makes a huge difference in focus control.)