It's not a bad game -- it is a beat-em-up, with the standard movement stick, and an attack and jump button, which can be used in the ways you'd expect. And it does have real voices and sounds from the show, nice new, crisp graphics, and (c'mon, it's The Simpsons) guest stars aplenty. You can bring the family members in for special attacks later on in the game's 25 levels, and there are even some mini-games just like the old arcade version. But it's not the same, and for $4.99 in the App Store with no free trial currently available, it's slightly disingenuous to call this "The Simpsons Arcade" when you're not really getting to play the old game.
If I bought this expecting a port and opened it up to find the respectable 2D beat-em-up that it is, I'd probably be a little disappointed. It's a good, solid game, and probably worth the price if you like this type of thing, but don't come expecting to revisit those glory days of '91 in any way but the overall feel.