Sorry but it make sens for a WIP but not a discussion about an engine. also making few Wip in different forum is kind a weird but let's drop it now.

Anyway Ratchet you made a excellent point, doing a full conversion game is harder than it in Unity for example. People are complaning about the lack of documentation. The community is fairly new and there wasn't so much total conversion mod so it's kind of hard to find valuable data on how to do anything from scratch. UDN tutorial are ok but it's kind a poor compare to other engine. Epic is working on it. they already did a a bunch of new tutorial with 3d buzz. the one DC9 is talking about.

So yea giving a real opinion is really important for people who never tried this engine.

The material editor is really powerful and even if Sorcerer did point out that it didn't explain in what interesting. The node based material editor allows you to create effect and combine different shader so easily I couldn't wonder how I would have done my shader in hlsl. So it's really easy to get you game a next gen look. There is a downside, basically you can't do everything you want in the post process editor. Doing a sobel shader wss a nightmare. I spend 3 days trying to create it. Converting hlsl into node is not that easy. But I did it.

About the car stuff is not that easy if you want to bring your own vehicular in the engine. To add a viper car is just a drag and drop but setting up your own car with physics isn't a trivial task.

You can do a lot with the UDK but you need some extra work to get you game in running. the main point is you aren't limited to the engine.

The shadows are problematic too some issue with large outdoor area. don't expect to do the next crysis or such.

here an example of full conversion.

http://www.moddb.com/mods/airborn/news/first-release-of-airborn