Soon as that's public there's bound to be heaps of people clamouring to build a mod that removes potions/etc and expands things in a more natural direction.
I played it a while back expecting minecraft in 2d, which is absolutely isn't. It shares superficial similarities but its emphasis is wholly different.
But I played it again more recently, being a bit more patient. and it's pretty awesome. It has far more depth than minecraft - there's a reason to keep exploring, you can find artifacts and stuff which helps you progress and you can trade and materials keep being useful (I mean in minecraft it goes stone > iron > diamond and then nothing. And you can get to diamond in like an hour of play without breaking a sweat).
You can build in Terraria (in fact, you have to - your house serves a purpose (multiple purposes actually) unlike Minecraft). But building is not the point - it's not got that feeling of taking on immense building projects you get in Minecraft.
It's more about developing your character by getting better gear. Which necessitates exploration and so on. If you fancy it all, give it a pop!
(Has host & play multiplayer built in (works when pirated, too))
Mods is a separate thing though. I don't think modding a game to be what you want it to be is the same as playing a well-rounded, cohesive, balanced thing. Also we'd all disagree as to what mods to use.
Not a huge amount new for buildery freaks:
* Slabs and stairs can be placed from underneath to be upside-down.
* New Redstone lamps - glowstone that can be turned on/off.
* Torches (both types) can be placed on top of glass.
* Double doors now work correctly.
There's a new world format, which is more efficient and doubles the max height to 256 (extra 128 of sky - sea level remains at 64; existing worlds are auto converted, and the terrain generator doesn't yet take advantage of it).
There's a new jungle biome, which is a lot of fun to run about in, and all the mobs have got updated AI, which makes things more interesting in general.
There's also a whole bunch of village-related updates, including aggressive zombies and an iron golem defender.
There have been relatively few updates to the enchantment/potion stuff, which is hopefully a sign that Jeb isn't wasting time on that nonsense.
Oh, and Notch has done the sensible thing and hired the Bukkit team - they're now Mojang staff, and (after completing Bukkit 1.2) will be producing the official Minecraft API.
So yeah, probably none of you still play the thing, but figured this was interesting enough to mention in case anyone has been thinking of getting back into it.