Can anyone elaborate on some of the things that are missing since then? I've got a 5-year-old who loves Minecraft and we've talked about modding but it just doesn't seem very approachable for a child that young. TrueCraft running on .NET would be considerably easier for me to introduce him to...
The "Adventure Update" and future updates in the same vein: hunger, enchanting, RPG-esque elements, etc.
Also, some of the major redstone additions from the later versions, which are the ones I'd miss most.