I fall pretty firmly on the "pro" side when it comes to an opinion of the Union Club.
It is indeed a bastion of Cleveland's long-departed halcyon days of over a century ago, when steel and iron ore brought men and money to the area. That's what makes it awesome!
You should come here to gaze up at the 20-foot ceilings, corinthian columns, and gigantic oil paintings; to enjoy the plush leather furniture, fresh linen napkins, and delicious (and moderately priced) food; and to revel - even if just for an hour or two - how the other half lives.
You can't come in here without a member anyway, unless you're part of a wedding reception or some other event guest list. Either way, you're associated with the bourgeoisie in some way, so embrace it. Eat and drink well. Network. Be comfortable.
I will definitely be back.