I've just upgraded to the new version of Admob.   I say upgrade, but what actually happens is you get a new Admob account, and then it imports your applications, leaving your data in the legacy Admob.

There was one issue, which is worth mentioning.  Ages ago I used my Google account to apply for an Adsense account (for this blog in fact!). It was rejected as not being the right type of content, which wasn't really an issue at the time, as I only applied to see what it did.  However, I couldn't upgrade to the new Admob as I had a pending Adsense rejection.  It did invite me to reapply, but other than that I couldn't progress.

To get round this I had to create a new Google Account, which was a bit annoying, although there as no problem linking this Google Account to my previous Admob account once I'd upgraded.