Tried to build my heavily customized "minidistro" with the new alpha....
Here are my comments and experiences (yes I know it's the very first alpha)
-  biggest problems for the buildscripts were the changed drive names (hdax --> sdax) and the new /run root-level directory that I forgot to include in the remaster.
-  boot time is improved (8 seconds from start to logon screen is not too bad for a 9-year old desktop).  Also shutdown/reboot time is improved.
-  the Xorg-7.5-3d.tcz extension is missing, so I dropped 3d acceleration for now.
-  OSS sound does not work as the download in Appbrowser fails with an "MD5SUM Error: Error on OSS-modules-3.0.3-tinycore.tcz".  I prefer OSS as in my experience it consumes less memory, initalizes faster and is more reliable than ALSA. 
-  Then tried to build OSS myself, like I did without problems in TCv3, but failed.  Reason as far I could determine: incomplete kernel headers, missing stuff that is present in the Tinycore version 3 header files (like some makefiles).
-  Then tried ALSA.  If you click the "Depends" tab in Appbrowser it still lists obsolete dependencies, like alsa-modules-2.6.33.3-tinycore.tcz.   But if you try to download ALSA it downloads the correct modules.  It seems to download even more than what is mentioned in the dependency list (like the v4l-dvb-3.0.3-tinycore.tcz extension)
-  ALSA didn't work first time.  It seems I have the same problem as what was mentioned in this post:  
http://forum.tinycorelinux.net/index.php/topic,11224.msg58729.html.   The mentioned depmod.tcz extension is missing in the v4 repository, but after copying it from TCv3 and installing it I got the sound working.
-  when I boot the original Tinycore ISO I experience a slight but annoying issue with the left mouse button: it only reacts if you hold it down a couple of tenths of seconds.  A short click does nothing so the system tends to miss clicks.
Apart from the aforementioned issues, the new alpha runs absolutely perfect: internet browsing, flash, fullscreen movies, sound etc. etc.   For a first cut it is fantastic!
Keep up the good work!