Honestly, in general it feels way less "professional" and more "bloggy" to me... partially because of annoyingly large fonts and lack of borders, mostly because of removal of details (linode ID, job ID, host start/end date of job, the host load meter, modification dates in DNS manager)...
The fact that you have so many options hidden in sub-screens now is quite annoying too, but it's not a killer. I'm also feeling kind of uneasy about having "Rebuild" so easily accessible in the main tabs, especially as "Deploy Distro" is still available in the disk image administration section (i.e. the new "Advanced Configuration" screen).
Things that I feel really, really should be back is displaying the physical host ID in list of nodes and the dashboard (generally, what was in the Host Summary widget in old manager).
And while you're at it, keeping the transfer usage bar in the dashboard would make it easier to keep eye on, with no need to return back to list of linodes. On the other hand, it seems that we finally can open a control panel for more than one linode in parallel.
Upon opening the DNS manager there's a tiny cosmetic annoyance, that is it sorts the domains by database ID or creation time, not by name. Of course ot can be easily fixed by clicking the column name... but why did you hide the modification dates?!

They're quite essential to me so I can notice when one of other users edited something... Having the reports from Check and Zonefile inside the UI instead of as plaintext are a mixed gain... but I guess that you prefer people to use API for any kind of (semi-)automatic processing.
TL;DR: Old one provides quite a lot of details the new one doesn't, and in my personal opinion has a better look&feel too.
Sorry for not being all happy over the new one, but that's what I honestly think of the beta as of today.
PS. I know there are "workarounds", like linode ID in the RRDtool graphs and host ID in the Lish login tab... but that's not really the point here.
EDIT: Some of the typos.