I used an F3 (non HP) with MD-4 for many, many years. I bought the F3 in 1983, when the exposure compensation button used to pop out. They redesigned the shaft of the button so that it doesn't pop out anymore. After more than 30 years, my original LCD and circuit boards still work just fine. I wear glasses, and never had a problem composing with the original finder. The meter display is nice also, in spite of all the haters out there on the net. I have a Nikon F2A now, and I find the tiny meter needle and shutter speed readout hard to see.
The MD-4 is heavy, but when it is on its batteries power the camera too. I had the NiCd battery pack in it, which allowed speeds up to 5 frames per second (6 with mirror lock up). More importantly, you can shoot in temperatures down to -20C with the NiCd pack. Another benefit is that the motor can rewind your film for you - very fast. If you have the correct back on your F3, it will leave the leader out. This is useful if you change film types a lot.
Other benefits - TTL flash, automatic shutter speed setting to X-synch speed with Nikon flashes.
Easy double exposures merely by flicking a switch.
Cons - meter display light is difficult to activate - only works when the meter display is on, and you hold down that little red button at the same time. Well, the F2A doesn't have one of those at all (unless you buy the meter illumination accessory), so there!
Camera meter won't work until you get to frame 1. This is to prevent hours long exposures in AUTO mode when you have your lens cap on, and you are trying to wind on a freshly loaded film to frame 1.
Putting a Nikon flash unit on ruins your ability to use the TTL exposure compensation.
It's an electronic camera, which means it is battery dependent. Nikon did give you a 1/60 mechanical speed for emergency use. Worse, people discount electronic cameras in favor of mechanical ones, so the resale value is lower than that of a comparable F2 or F. There is no collectible value, compared to the Nikon RF cameras such as the M, S, S2, S3, SP, S4.