I am now exceedingly upset as I have actually created the Yellow Castle set before on Blockland.
I used it as a hidden castle in a Medieval Roleplay build. It fired A barrage of spears from the Circular parts on the higher tower. I also evented the Drawbridge to close up and down.
The main problem with building things directly from these is that they are never of a good size.
They're either an old Lego set, which were generally just bricks in the shape of things as if they were more 2D. They're only good looking face on and can't be used for anything other than please aesthetics.
If they're not one of those, then they're a slightly larger build like the Yellow Castle. The problem with these is that they're not big enough. If you'll note, a Lego person only requires two spaces really to be set up anywhere. (Yes, I know they're arms combine to take up three spaces, but essentially, they're not moving). In Blockland, a Blockhead takes up three spaces and moves, this means it constantly needs it's 3x3 brick space, compared to the Lego person who could only need a 2x3 space as in a set, Lego people are just stood still in place.
Essentially, this means that something like the Yellow Castle, a relatively good building, is too small for actual comfortable use. The walkways leave you almost falling off and gaps are too close together to squeeze through. You're left with a tiny space to maneuvre in which makes playing with them relatively difficult.
The last type is again, bigger (And probably lacking space for maneuvarability) but uses bricks just not possible in Blockland, or not yet made. When you're wanting some form of odd circular shape with chunks missing from it, you can't really make up for it. The smaller simple things can't be replaced without use of props, either. It's just an unfortuante ordeal that Blockland couldn't support them or they're just not worth making for the game.
The second problem to do with bricks is that in Blockland, everything is stuck to a strict Grid. Everything is directly either in the X, Y or Z axis, in a straight line. In Lego however, you can easily have a piece that moves along diagonally. You can have roofs that are shaped at an angle, and then have bricks coming off of them at 90o angles. Things that just aren't possible in Blockland.
Because of this, trying to create a working and extremely attractive Lego build is really hard, and it's damn near impossible to find a good Lego build out there with instructions that you can get to, that manages to get past all three of these problems.
Anyways, after that rant about how I have problems doing this, I guess all I can say is well done, I guess.
Even though of course you're working off of instructions, it's still a relatively difficult thing to do.
It's a problem enough in Lego when you're building something and make a mistake, it's even worse in Blockland where you can't as easily go back and change it.
I especially know that the YellowCastle is relatively annoying and time-consuming to build.
Again though, well done.