Theres nothing wrong with the modern stuff, I'm constantly amazed at how much horsepower they are extracting from small cubic inch engines and also how much mileage they are capable of extracting from large cubic inch engines.
I tested a brand-new "Bullit" themed Mustang back a few years and was amazed at the seat of the pants excitement and then equally amazed at its around town civility. A friend of my son has a later model Mustang GT, not the fully blown model but a pretty hot when you mash the throttle down. I found they need to be driven agressively to get the most out of them.
I never was a huge Mustang fan, I have a '51 Ford two door sedan with a hopped up flathead engine, old school hot rod. A buddy of mine that is a first rate builder put together a beautiful '65 Mustang Fastback, GT-40 type 351, late model 6 speed tranny, 9" differential, huge disc brakes all around, engineered suspension, electric exhaust dumps...its the ****. He claims he's only into 20 grand but he's done nearly everything except some of the suspension components, he did all the body and paint and its truly gorgeous, black with gold racing stripe...thats my idea of a Mustang.
From everything I've heard talking to everybody that owns one including one of my wife's girlfriends that drives a late model GT, white with blue stripe. She calls it her "Man Magnet", big ugly girl like her needs all the help she can get. Everybody that owns one likes them, only one guy I know had one and traded it for one of the late model hemi powered Challenger or Charger because he always wanted a Hemi.