I am glad to know that HF20 is coming. It was a much awaited thing as we were reading about it time and again. I think some issues, related to Steem platform, were addressed effectively and some others were totally ignored. 
Positive changes: implementation of Resource Credit in place of bandwidth system, procedure of account creation, change in dust vote threshold, removal of the minimum sp power down restriction, change in 30 minutes curation timeline, change in self voting reward to some extent, time limit of 28 days for internal market orders, removal of 20 second comment limit, decrease in delegation cool down period, fix for double voting exploitation, increase in account voting power precision, upvote lockout period and other witness related issues. 
However, there are many issues which were left untouched. An issue like self voting was addressed but it was done not very effectively. No limit was imposed on self voting. Also issues like vote selling, circle jerking, downvoting without assigning any reason, no payout for quality posts were left untouched. These were the core issues which many users wanted to be addressed and fixed. I welcome change but this change cannot be said a radical change. It is an old wine in new bottle. So, it is a bit disappointing.