We have learned that the Start menu is now transparent, but that's not a complete surprise to us, other genuine surprises include a new way to receive updates over P2P, App management is also quite a bit improved and Task View received some power-user options.

Click image for larger version. 

Name:	screen_shot_2015-03-14_at_11.17.09_am.jpg 
Views:	48 
Size:	133.0 KB 
ID:	14468

We're still learning from this build, but another update revolves around the Insider Hub app, of which itself is still in a testing phase and getting constantly updated. The Insider Hub now allows you to track your progress on the feedback you are submitting to Microsoft with the following stats:
Read more: Windows 10 build 10036 includes update to Insider Hub for stat tracking