I love EM games!
Good:
Easy to explain rules-Most have a ruleset along the lines of: "all you gotta do" and then you try 1000 times thinking you are Maxwell Smart and *missed it by that much*.
Prices are very reasonable. Pretty easy to sell without taking a financial hit or finding people willing to spend 20K on a game.
Original, very colorful art.
Fun to play with friends-games usually are very quick.
Bang for the buck is unmatched. Spending $5000-6000 in EM games could give you tons of options versus one brand new game.
No issues with pooling of the clearcoat. Playfield paint has already cured for 50+ years
Bad:
Some parts can be unobtainium. (Maybe that is an ugly)
Can be intimidating to fix if you are not familiar with how they work (Actually applies across all types of games)
Ugly:
Well, that is in the eye of the beholder. I think some styles of EM art are hideous, but I won't say which because I am sure there are some that would think the exact opposite.
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Whatever you decide, enjoy