I’m a computer programmer by trade - you have to understand that a DAW is a niche product in quite a small market - it will never be polished to the nth degree it’s simply not commercially viable to do so - unless you want to sell it for £2000 - in which case no-one will buy it - I must say I’m astonished by all the features in Cubase 8 - yes there are bugs but wrap your head around how many millions of lines of code are required to implement all these features and yet still be user friendly enough to not slow the creative juices of a musician. IMHO Steinberg Cubase 8 is a modern miracle.
As for it being unusable - that part is a lottery based on what features are essential to you and whether it gets on with your computer/drivers/sound interface. My CB8 experience so far has been very good - a few niggles aside. I’ve not experienced a single crash and I still use some 32bit plugins (shame on me!)