How reliable are the computers suggestions so far as what tile improvement you should set your worker to doing?
It might be amusing to play a game where one only follows the tile improvement advice for worker actions, only settles cities in recommended locations, and only makes the research/construction choices suggested by the advisors. I think this has been done before, but not for a while.
Simple example is banana in jungle - what is right improvement?
In this case, the choice is more do you improve it or not; your not allowed to put anything except a plantation on bananas, which will clear the jungle.
The same goes for every other resource improvement in Civ V. *
* With the minor exception of strategic resources you don't have the tech to see yet.
Yes, bananas are to improve or not to improve, but was used as a simple example compared to the regular TP vs farm vs mine choices. But let's talk about resources and eventually bananas
The automated workers are useful in maybe 80-90% cases and I have no problem recommending them for the beginning player so they can focus on learning the many other aspects of civ5. For people playing on harder difficulties these workers do too many "wrong" things because we typically have a long-term strategy which the AI has no way of knowing. The auto workers are really fond of food and seems to favour improving those tiles in most cases, but does not seem to take into account your strategy and other gameplay aspects like happiness control or faith/pantheons.
Automated workers are also fond of exploiting resources, and generally that is ok, especially where things can be reverted. Jungles and forests cannot be unchopped (with an unmodded civ5) so if a worker screws up you "lose" that tile for the rest of the game. For certain strategies it is a significant boost to keep jungles' science boost, but the auto workers will see a banana, become hungry and will step over to add a plantation for more yellow curved food. And you notice too late, naturally, when you get the message "14 hammers added to My City".
I want to use auto workers because it is not fun micro manage them after turn 100-150 when the critical resources have been handled. It is mainly a UI issue I think - the two worker options and preferences are too few. Maybe a screen to define basic rules for workers could make them a more viable option for turns 150+. Some of the things that annoy me are especially the destructive operations, how workers handle road quests and priorities hammer/food/money/science/luxuries, ... Most of those should be possible to handle in a single screen combined with some rules about what areas a certain worker should focus on.
I have not tested auto workers with hiawatha or the celts, do they take into account forest preferences?
The automatic improvement algorithm is horrible. It cannot optimize road placement by taking building an "Y" connection to three cities into account. It will shop too many jungles instead of putting trading posts on them. It cannot differentiate between own cities you want to grow as much as possible for specialists and cities that you want too keep small and just bring in gold.
Especially in the beginning you need to consider carefully what tiles to improve. First priority is to make sure city (especially capital) has enough farms. Second priority is some production. If you want to have a good game micromanagement is essential and in my opinion good also for the immersion. Turning on automatic improvement is not only inefficient but also boring.
The only automatic movement I use is for exploration once I think I've the biggest other civs. This algorithm is fine for the random movement required to find the last natural wonders. I also find the shuttling back and forth of the map view that three or four ships in all parts of the world makes for disturbs concentration.
And you notice too late, naturally, when you get the message "14 hammers added to My City".
I never trusted automated workers in Civ3 and I still don't trust them now haha. Every mine, farm, and trading post, road, and whatever else is hand picked by me.