Odoo v8 is still quite unstable. I tried to use it as a real life ERP (I know, I know ... beta and RC are not to be used) but there have been many problems in the simplest of places.

For me the warehouse changes are so inconvenient that I'm planning to drop using odoo at all. In v7 the serial number functionality was a lot easier (e.g splitting purchased quantities during reception). Now I have to use this freaking inconvenient Barcode view and I don't want to. Also the missing flexibility of managing cost prices of products is very bad thing.

They have done quite a huge work but they shifted their focus to nice-to-have functionality (e.g website builder) and not to improve the core. Just my 2 cents.

I do not speak for odoo but according to what I have read there has been major changes in the Warehouse module.  Of course the CMS (website) module is new and two modules have been rewritten to verify the validity of the new API (the account and event modules).

Of course you can always look at the OpenUpgrade 7->8 module upgrade status to see where scheme changes were made and therefore module changes.