I did buy it (the small one, two days ago) and so far it has given me 0,73USD.
But I bought it since in the conditions, it says "Upgrades will be extended (adding 7 days), in the event that you have received less than $2.99 / $19.99 worth of 1% ads. This extension will occur as many times as is necessary to achieve at least the minimum delivery ad quota."
I saw that too and at first seems confusing but i bought the 0.05 upgrade to receive recycled ads, on the first time i got 2 ads $0.002 and $1.54 and the upgrade worn off, so i bought it again and I got many $0.002 but it is still active ($0.20 remaining)
I think that all of the upgrades that can extend their time are worth the time only if you commit to keep viewing ads.
In the last week I got $2.5 in total (no external investment from my part), reinvested everything and today I got so many $0.04 (5 at once I believe) that now i have $1.20 in one day
Of course they had a problem in the last days and the ads came all in one swing, but still thats almost 20x what I did on my first day