My comparison between A18/17/16-- on building: down the hill
When we put all personal judgment aside and rely only on facts, it comes down to the fact, that till A16 i could build bases up to sizes that the game engine threw the towel with "too many vertices".
In A17 i do not have the ability to build even far similar that big. The game engine does drop the frame rates long before to unplayable levels (with which i mean below 20 fps). The biggest bases i could build in A17 are the same size as the smallest ever bases in A16.
In A18, the same principle applies, but again halved in size limit in relation to A17.
Thus, building at least became a lot more miniature.
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That said, there is some kind of build-in end goal to achieve: If the cultivated area gets so big that zombies cease to spawn on horde night despite doing everydays work at the base, i usually consider the game won. Since the funpimps reduced the size of the spawn area for horde nights, that goal keeps being achievable with higher alphas as it was with the lower ones.
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Gardening in A18 has become ugly. While it can be seen as a type of challenge to produce one single tile of gardening area out of a whole mountain of earth (in extreme contrast to A16 and A17, where you could build up to three gardening blocks out of one shovel of earth), the resulting blocks are simply ugly. They do not even blend in to the landscape.
You can't build such things like flower borders for pure aesthetics any more, since that would require you to scrap (real , not proverbial) mountains of landscape beforehand.
I used to finally fit the cultivated areas with flowers and yucca. Well: I will, of course, with A18, too. But for sure not with vanilla configs. As always the game needs thousands of corrections until it finally makes fun again. As with every alpha so long.