The open playtest started today, but many people (me included) are unable to download the materials. So I can't comment on anything in the playtest materials. Sheesh!
Come on WotC, you could have done much better than this with the downloads. You had options. Beef up broadband capacity, or do it a less expensive way such as quietly opening it up in waves throughout the week to cut down on the server load you had to know you were going to get hit with when launching the playtest.
Looks like I'll have to wait until they can fix the issue before diving into the pros and cons of early Next.