I’m not huge on the Simic manland, and I must say that the Orzhov counterpart isn’t terribly impressive either. It looks like R&D decided to actively tone down the power level of the enemy cycle.
The value of manlands is that they allow you to consider lands as psuedo-spells and that they can pressure planeswalkers even on an “empty” board, but Shambling Vent is kind of lacking in this department. A 2/3 just isn’t much of a body, though this is still an upgrade from Scoured Barrens.
I have high hopes for the rest of the cycle, though thus far the lands spoiled aren’t living up to the originals.