I have just started using park4money and I'd thought I'd share some thoughts/findings.....
1. For each domain, you have to register as a new user. There is not the option to have all domains in one control panel. This means logging in to each domain individually and inputting adsense ID, keywords etc. Very time consuming indeed. (the park4money team actually set registered each domain for me, but Ive still had to set up each one individually).
2. You can add adsense channels to each domains.
3. The templates rely heavily on free articles etc which are very generic
4. It took less than a week for a previously sedo parked domain to be included in google results.
5. One domain that had next to zero type in and no revenue when parked has paid for itself in adsense earnings in less than 4 days.
So, in conclusion, it is very time consuming to set up, the templates are just OK, but pages are very google friendly and do attract click through.
I will stick with them for now as Ive seen some benefits and the p4m team appear to be very helpful.