So, everyone agrees that AmigaOS 4 have advantage here, over all the other AmigaOS alikes.
To answer the original poster - how is OS4? - Better than AmigaOS 3.
More:
16. Better preview functions for files in Workbench. Opening drawers and selecting Show->All files and View by->Name shows a resized icons on the left of the list for the different files. There is also the new Type, showing the type of file or drawer - Ascii, Project, Tool, Drawer, Zip, Lharc, Patch and many more.
17. Automatic refresh of drawers. If you download a file to RAM: or anywhere else, no need to go Window->Update to see the new file.
18. Screen Edges resistance - I find it very useful when placing windows near the edges of the screen. I still can put them outside, but it is harder, saves my lots of time.
19. Transpararency effects - for the people who prefer candy effects, they are there, highly customizable.
20. Icons rescaling - built in and supported by Workbench. No need to rely on third party software for this simple task.
21. Better shell - no need to remember exact names. Press the first letter or several letters of the file name you are looking for and then press Tab until you find it.
22. Execute Command from Workbench gives the possibility to search for the file with ASL requester - no more need to remember exact names, paths for the file you want to execute.
23. Detect settings of monitor automatically. No need to search the monitor manual and see what's the max supported modes. AmigaOS 4 will ask the monitor about this. You still can try higher resolutions with different refresh rates, at your own risk.
24. High resolution mouse pointer with dropshadow effect.
25. CDRW support built-in the OS. No more need to rely on third party software for backup to CDRW.
26. DiskImage handler. Click on CD image to mount it like a real CD. No more need to rely on third party software for this ordinary task.
27. Themes - don't like the ordinary AmigaOS 4 look? Click on the present themes or download some of the Internet. Don't like the new look? Double click on the Revert to Last Saved icon to restore your old theme.
28. Boot jingle - done by respected japanese musician.
29. URL handler.
Of course the list can go on and on. For the last nine and half years, since AmigOS 3.9 was released there are lots of improvements in AmigaOS. They are part of AmigaOS 4. It will take a bigger thread than this to list, comment and discuss all of them.
Not trying to say that any of those would be bad in any way, but you can get many of those for 3.x aswell. 3rd party or not, doesn't make much difference to me. In some cases, it's the very same "3rd party program", just bundled with the OS (I guess you mean openurl.library with URL handler, for example?)
But thanks for excluding screen dragging from the list :-)
