It's kind of debatable whether or not the success they've had is earned if you separate their disastrous PR from their actual developed content.
On the one hand, they've taken a lot of things from Terraria and improved upon them, the ease of construction being a primary factor. The monster part mashup could also lead to some very interesting things should they decide to play around with multiple monster sizes, and multi component setups. Why are most things quadrupeds, with the rare hexapod? Why not chain together torsos, have multiple heads or arms etc. Give them specific animations. Link abilities to monster types in some way, because, seriously, the scrawny half meter mouse-thing using Body Slam and taking out half your health with appropriate-tier armor is at the very least incongruous.
On the other, they seem to have also forgotten so much, again from Terraria. The UI functionality is as low, if not lower due to several new features, than Terraria's when it launched, and they now have the benefit of hindsight. I'm merely going to mention the random desync that even happens in singleplayer, since I don't know how easy something like that is to fix, nor what could be causing it. The actual combat would feel less janky if that were resolved as well.
They do seem to legitimately want to make an entertaining game, considering all the toys they're working on, and they are still reportedly working on it, unlike vaporware like Towns, or software that's of laughably poor quality on release and examples of which we can all list from the top of our heads.
The problem is what exactly they are working on; there doesn't seem to be a deadline for some feature that doesn't get delayed or tossed out entirely; without actually being there it's hard to say whether they actually know what they're doing but are overly optimistic on their workloads, or they're disorganized, or inept, or are losing a focus due to feature creep, all of which are worrying prospects.