2.: sculptys: independent from tool (sculptypaint /blender/wings) or wa of construction:
objects like six-or eightsided rotors, stars may be in editor totally ok, when imported to SL the sides are different.

3.:sculptys: (dunno if this is really a bug):
Objects behave like builded from bumpmap, not displacement-mapping.
That means: you hover over seats or lower parts of stairs, you can't walk through a hole in prim and such

eventhough minor problems, I count them as major. They stop developments I worked partly several month on.And whole SL content is made from objects users develop.
—
examples:
point 1:
making portholes at a ship side:
If using SL prims instead you have to build the part with hole as a suqare, because you can only define width, height and position of a hole over the measurement of the object.
that means at least 1 prim xtra to make a rectangle wall from a square, same with a wall over rounded hulk part. And glass of the portholes must also be from from xtra prims
=> 1-5 prims per porthole extra to solve that problem on another way

point 2:
building paddles for a paddle steamer:
with sculptys you can save 4 or more prims . If using multiprim build from SL parts instead the paddles often play mad when using rotation script.

-----------------------------edit---------sculpt--------------------

• sculpt load takes to long.
• they must be big, otherwise the begin to deform when you move only a few steps away,
  independent from your grafical settings.
• seems they are now aut-smoothed, at least on mono.
  It will take hours to sharpen those desks I made, eventhough I always use same steps for
  base modell.
  -the more you smooth/subidvide them in editor the uglier edges you get
  -----edit 2--- grafical positions----
• problem: objects like cylinder, sphere and such have a different shape of curve even
• problem: I now have sometimes totally different measurements to work with, when building a big plane the concave sphere segment at front was much bigger than the tube of plain's body, eventhough they had same diameter (maybe same as the other problem)
• problem: position--> on attached pic there are a pole (ship mast) and a torus around.
  they both have same xy-position, but don't fit.
  That appears normally when editing an object that doesn't stand directly north-south or east-west lined.
  But it can also be a "fake" -error, as sometimes when moving a vehicle around not all parts follow that movement.
• problem: when using the turn command the axis symbol is always there where needed.
  But the axis position symbol always stays at middle of prim/object..So it's often outside the area you are editing, making it difficult/impossible to edit several parts/fixes by push/pull