Trying to figure out if this is a good watch for my father's birthday

sheepdoll

I would not think a hummer would be a good first watch. They are more of a novelty and a bit esoteric. Of course if one is into Accutrons or outside the box things, then it does make for a unique gift.

X350 XJR

I don't see any issues with the watch. However they need a specialist to service or repair them.

I too would not recommend one of these as a first vintage, especially when there are so many other options available.

Spruce

I live in the UK and have three. All are a delight to wear and accurate.

Modern Renata batteries generally work in them and new caseback gaskets are available (here I get them from Cousins UK) but it helps if you know how to unscrew the caseback and battery retainer so that you can replace the battery yourself when it needs changing.

I f*****d up one of mine when trying to adjust the time (just careless stupidity) but the service and repair cost £300.

That said, these are great watches if you can get one in nice condition.