I'll guess it being in 2D was what threw it for me. The game is probably enjoyable if you're into it, but Terraria just didn't grasp anything out of me.
It's 2D in more ways than just graphically. While there are indeed ~600 items and ~100 monsters, since a lot of these resources act exactly the same in reality this content is a fifth of what it appears to be. There's no 'depth' in the actual content itself, and it winds up being consistently more of the same thing.
To me, the best update was the addition of potions and overworld chests with their minor trinkets. It was additional content near the beginning of the game where it was needed, but this depth of content starts to fail itself and return to bland-crap at, as I've obsessed over, "Hardmode". And the excuse, straight from the mouth of their graphic artist's personal understanding, is as follows:
A rough quote from Tiy said:
Hardmode is full of difficult monsters to make sure players are never 'unstoppable'. To give them something to keep on doing while they wait for the next version.
Really, they never actually gave a crap. These were distractions from the fact that they didn't actually add anything new. While hardmode contains 'rematches' with bosses presenting seemingly new AI, the reality is they used the same old bosses and made them so erratic that it was impossible to decipher their movement pattern, as you could scarcely avoid them hitting you at all. And this was further bastardized by the fact that you had to gather uncommon resources to create the
consumable item to summon them, and they disappeared if you died to them, rendering your past attempt a net loss to your time and resources.
Enemies and items are just the same as before with some sped-up and stronger versions, some of them done so solely, and FACTUALLY to artificially lengthen the game.
Imagine if SRB2 never moved beyond crawlas and jetty-syns, and instead opted to make later levels contain these same enemies, only with multiple hitpoints and Mystic-realm-second-quest movement speeds. If the game was stuck in 1.09.4's level layout, and they decided that was the final version --
That is Terraria. An acceptable tech demo, but nothing more.