I thought AdMob has there own mediation services now (from the ads I see on AdWhirl) I am sure someone from there is lurking here and can answer better than I how it works. I was hesitant to try it out initially since the there was a relationship between AdWhirl and AdMob and AdWhirl was not working for me I stayed away. Maybe one of these days I will compare my experience, but here it is in a nutshell from the outside looking in.
I personally use AdMob as an ad network from within MoPub (I use MoPub to mediate and now serve house ads, I use AdMob is one of my networks inside of MoPub (among many others). All of those networks I configure to compete against the real time bidding marketplace in MoPub. This is not meant to be an ad for MoPub either. I had a a real bad experience with AdMob CPM initially out of the gate, but that is not true as of this past 14 days (maybe that is because we are consistently requesting more ads and care to make sure our CTR is up (in a legit fashion, ad placement, refresh rate, etc.) I adjust my eCPM settings on MoPub to determine who gets asked first to fulfill my request for an ad about once a week. It is certainly sufficiently complicated, and I am getting faster at it.
What I predict is that each ad network supporting mediation of some form will slowly pick all the features that AdWhirl gave and AdWhirl becomes moot, and the pricing is already low, since AdWhirl still works, just not the reporting, all it really is doing is serving config to your app to define ad request behavior, and you can pretty easily set up yourself given the instructions on the site, but it costs money.
And I think that serving reports costs money and is likely not worth as much as the data that is collected by AdWhirl serving configs collecting usage data, so that part stays working. That is my opinion. If you want reports from AdWhirl, you have to do it yourself (also my opinion, and an untested one at that.)
-Hunter