I have a restored Fathom, mint centaur, and HUO Medusa in my collection and I will say Fathom is absolutely worth it if you are into the early 80's games. I love all 3 games and can't imagine not having all 3.. they are that good and compliment each other very nicely.
If you play the living crap out of any of these old games, they will become "old" lol... I'm not surprised some have said that.. but I also have 8 other modern games (another wall) and I spend more time playing them and everything balances out.
Since we're focused on Fathom, I'll add my $.02- It's super fun if it's dialed in, and mine is dialed in (I have upgraded flippers/coils and is one of the best playing Fathoms ever in my opinion). I've owned it and the 3 for many years and I never look at them like it's time to go... I look at it more like it took me a decade to get 3 amazing samples of these titles and there is no way I'm letting them go now.
Get one and you'll love it! The art, speech, third flipper shot, locks, multi-balls, etc., are just pure gold.
Good luck with your search!