Board games and other games with single device local multiplayer have been a real hit around my house on the iPad. The large screen of the device really shines in any kind of local multiplayer scenario, and I've had a ton of fun playing everything from single-screen racing games like Danger Derby [$4.99] to excellent adaptations of board games like Small World [$6.99]. We were happy to see the original release of Catan for the iPhone last year, and ever since I realized how much fun board games are on the device, I've been looking for Catan on the iPad.
Unfortunately, there are two notable issues with this release. First off, Catan HD [$4.99] is yet another HD version of a game with no real noteworthy differences between the iPhone game aside from higher resolution art and a different UI. (Something several people on our forums are voicing their disappointment about.) Secondly, in the shadow of games like Small World for the iPad or Carcassonne [$4.99] for the iPhone, Catan HD feels lackluster in comparison.
The high resolution graphics don't look that great, and are made even worse by slowly animating between a few frames, giving the whole game a jerky appearance. Also, Carcassonne really set the standard for multiplayer options in a board game, and it's unfortunate to see that even the iPad version of the game launching without bluetooth or online multiplayer.
If you're looking to play Settlers of Catan without dealing with all the pieces of the physical game, Catan HD is a decent alternative, just don't expect anything more than the iPhone game running at a higher resolution.