Except, it totally isn't.
People tend to like Pinball Arcade because it has models of real tables that they love. But Zen Pinball 2 is better in almost every way otherwise, and on the Vita, it's just no contest whatsoever.
This is actually not true because the only table I ever played before I got my hands on Pinball Arcade was Medieval Madness.
* The tables in Arcade just have better themes while Zen feels extremely generic.
* The controls on Zen are floaty suck while Pinball Arcade is a ton tighter and more responsive.
* The physics are nowhere near as satisfying in Zen compared to Arcade - the ball moves faster and smoothly and collisions are handled a ton better in Arcade.
* Both the two points I just described lead to Zen being a lot easier and unsatisfying in comparison to Arcade in general.
* Arcade has a lot more longevity than Zen goals-wise, especially with ten table goals per table in comparison to the two to five in Zen.
* The real life voices and likenesses in Arcade are a leap ahead of the (mostly) soundalikes they have in Zen.
While there is better multiplayer integration in Zen, it is mostly for useless stuff (like the "team score"). You can't argue graphics because Arcade is trying to actively recreate the original tables - Zen can make everything look as flashy as it like, not to mention the two games are pretty on the level presentation wise.
And in terms of table library...most of the tables in Arcade are just more fun and addicting than most Zen tables. The only two tables that I can think of that drew me in within the Zen library are Plants vs Zombies and Epic Quest, meanwhile I can name over half a dozen in Pinball Arcade (Attack from Mars, Big Shot, Whirlwind, Cactus Canyon, Medieval Madness, Star Trek, Terminator 2...) I will be honest though, I don't own the entire Zen library, I only own the original concept tables, the Star Wars Pinball tables and Plants vs Zombies (no Marvel tables, no other game-based tables).