No, it's not a new game. You think I'm trying to be competitive with Shut Up & Sit Down or something?
Anyway. CTHULHU BITCHES
Arkham Horror was the original version of this game, released in 2005, where you ran around Arkham to try and stop the invasion of the hentai gods before their squadrons of flying penis monsters took over the city, and from there the world. After a few expansions, some of which turned this reasonably good game into a pile of smoking dogshit (looking at you, Dunwich), a new version was built around the same gameplay concepts--run around, fight off the hordes of waggling dicks, and figure out how to stop the elder god from either spawning or just ending all life on the planet.
This one, Eldritch Horror, worked better from the start just by having your investigators travel all over the world, since it took a stretch of the imagination to think Cthulhu or Azathoth or whoever would dump all their forces into the one city where anyone knew about them and gave enough of a shit to fight back. It was also designed to have a more streamlined gameplay process; things happen that involve the alternate dimensions famous in the Cthulhu mythos, but you don't travel there and move according to special rules, nor do different characters move different distances, and everyone has two actions per turn to handle anything they want to do--movement, acquiring items, resting, etc. Also, your stats are your stats; the min-maxing every turn, while sometimes useful, is more number crunching than most people need. Five base stats (which can still go up or down, depending on what happens) is plenty.
When you look at the game, and get used to the turn flow, it seems like it should go much faster than Arkham, which was a major selling point of the game. There are only three turn phases instead of five, there's no monster pile on the side that keeps adding to your odds of being utterly annihilated... there's just less to keep track of in general. Your action options are limited and easy to grasp: move, get a ticket so you can move farther, use your influence to buy stuff, rest to regain health and sanity, or trade with another investigator. (Some cards or investigator abilities add more things you can spend actions on, but those are equally easy to understand.) They even have bank loans available so that if you totally flub your influence roll to buy assets, you can still take on debt to get something, assuming all the risk involved (read: mob hit squads). It's designed better on a core level than Arkham.
And yet... this is still a game where five competent gamers can take three hours to finish, which is not really an improvement. Nor are you getting a ton of turns in during that time, maybe seven or eight total. And five players is not excessive; it plays up to eight, which is not recommended. It's like being used to driving somewhere with your grandma, then getting to ride with your brother, which is a more exciting trip that fractures quantum mechanics and somehow ends up taking just as long. That's unfortunate, too, because Eldritch Horror probably benefits more from extra investigators in terms of your odds of winning than its predecessor.
If you've never played either of these games, Eldritch Horror is probably the one you'll like more. It's easier to learn and understand, with fewer marginally useful mechanics. There's more story written into the cards, and less of a requirement that you have investigators with the best possible stats for whatever they're trying to do. It is, in short, an improvement in the you would expect a new version of an older game to be. But you do need to expect this game to take a few hours until you're experienced enough to tear through the encounter and mythos phases.
Score: Thirteen detached tentacle suckers laying dead on a cobblestone road out of nineteen