Well, I've always used FM2s and FMs. I also have picked up a FE and FE2. Due to all of the rave reviews that the F3HP and F2s receive, I thought I should at least try them out. Here are my preferences, in order, and why.
1) FM2n - fully manual, meaning few electronics to go wrong. Light meter is VERY easy to see.
2) FM - same as above but a bit lower flash sync, not really an issue for me though.
3) FE and FE2 - more dependence on electronics that can go wrong. The auto exposure is VERY useful at times, especially when it's tough to read the meter. Meter is easy and very informative in good light, a bear to read in poor light.
4) F2 - Nice camera, big, heavy, light meter easy enough to read, not as informative as FEs
5) F3 - Nice camera, big, heavy, light meter is very difficult to read. I have to specifically look for and at the meter. Illumination is basically worthless.
So, while the F3 has a loyal fan base, I do not find it particularly joyful to use. In fact, I'm considering selling mine - haven't decided yet. Will probably give it more time to grow on me, but not sure it will.
As other have said, $50, if it works, is a very good deal.