Okay so here's something that I have been missing the most in the past 6months with Esenthel.
The worst feature of the engine is the difficulty of finding stuff out by yourself.

I've worked with unity quite a bit and they have a wonderful script reference page that works perfectly.
I would suggest if you ever have the time or the resources to come up something similar. that way you would probably save a lot of time by not needing to explain everything to everybody yourself.

Script reference

As you can see theres a very good search engine and every command or function is explained very well with an example lines of code.

The closest thing esenthel has for this is the automated api which for me at least seems extremely difficult to grasp.

hm strange, I found Esenthel one of the easiest engines to learn You're right that Unity have great documentation, but in Esenthel you have many examples which explain a lot and all functions are commented in the headers but I can agree, such reference is a nice thing to learn from

well.. i could easilly do the same stuff as in the tutorials.
but when i wanted to do something really simple actions like rotating an object or change a material parameter it all became extremely difficult.
Basically not all the commands of the engine are in the tutorials.
I know the engine is not supposed to be a plug and play crap like unity..
Well.. if there's people that have had the same difficulties as i have, please speak up.
If I am the only one then nevermind

ps:
And as for the easiest engine:
I can produce the same demo as i have now in esenthel in tenth of the time with these engines:
Leadwerks
Shiva
Unity
UDK
DXStudio
Source
etc...

Still we chose Esenthel because of the price/quality.
Most of the same priced engines don't offer the same amount of features.

I would agree that some documentation on the API would be really helpful. The auto-generated API documentation helps some but it really lacks important information. One problem with trying to put together some decent documentation is due to the fact that the engine is still maturing and things change often. Trying to keep documentation up to date is not an easy process.
For many things, searching through the header files can be helpful but often it's still trial and error to see if something works like you think it will.

I think that what we have for a single human effort is already very good. I mean, we have tons of tutorials which show the easies way to do things.

obviously there are tons of other methods in many classes but the easies way to learn them is to experiment a lot.

what I mean is that trial and error is the best way to learn imho.

building up a documentation like unity's one is a big effort for many people to work on.