I haven't played Minecraft, but did pick up
Junk Jack which is similar. I can say without a doubt it's been worth every penny. It's probably in my top 5 favorite iPad apps, which says alot. The developer is also constantly updating it too.
Here's some current features:
Features:
* retro style pixel art!
* beautiful sound tracks from Bright Primate
* intuitive controls: swipe to move and tap to interact with everything!
* dynamic day/night cycle
* never get lost with customizable signs
* advanced farming system with 30 different plant types
* 120 recipes for cookable foods!
* tint cloth blocks with 15 color dyes
* underground biomes with unique graphic style and monsters.
* placeable and throwable explosives that can destroy buildings, landscapes and monsters!
* critters and enemies to fight (more than 45 different mobs!)
* a fully featured lighting system together with many different sources of light and global lighting
* 3 slots for infinite worlds that you can generate and explore, every world is different from any other!
* procedural generation which creates beautiful worlds with plants, caves, different biomes all around the world
* a double layered world which allows to customize background and foreground of your creations
* many ores and shiny gems to help your adventure
* many hidden containers full of treasures
* more than 800 treasures!
* more than 420 crafts!
* more than 370 block types
* many elements to decorate your houses (like sofas, tables, wardrobes, paintings, statues and many others)
* an in-game discoverable book to teach you how to play and the recipes available
* shelfs to place items around just to make your buildings shine
* minimap (with a really zoomed out feature to allow you to share your creations)
* runs fine on older gen hardware