OpenBuildings Pipe/Duct Sizing

I have used Hevacomp Building Designer & Netsys in the past and having tried to purchase the software again understand that it has been replaced with OpenBuildings.

Can anyone advise if the software is anything like the building designer / netsys of old i.e similar in use, better/worse etc... Is it easy to transfer from using one to another or are there big differences/learning curves?

Thanks in advance