Cant say I've spent a huge amount of time with Terraria myself.
I went through it once, and then..... for whatever reason the replay value just vanished.
Though, part of it at least was the game's combat and power progression.... at some point the combat stops being about "dodge these things, hit this guy" and becomes more about "fly around and click over and over, dont worry much about getting hit or where you aim, you're basically a god now anyway". The bosses in particular, didnt like them, those fights were usually the most mindless.
Not that vanilla Minecraft is much better about it.... put on a full set of iron armor, and you're nearly invincible. Put on diamond armor, and you ARE invincible. And the bosses in that one are pretty stupid as well.
Though I think the one major thing that bugged me with Terraria was that the digging aspect was MUCH too slow, particularly considering how the world is made up of lots and LOTS of really tiny blocks. If Starbound still had that issue, honestly I probably wouldnt be playing it, no matter how good the rest of it is, since I'm not the patient sort. Fortunately though they did away with that issue with that game, as even the weakest picks dig out a 3x3 area instead of one tiny block at a time. Though, for all I know, maybe they fixed that somehow in Terraria, but from videos I've seen of the game lately, that is not the case.