The only downside to Google Adsense, is the fact that a person actually has to click on an ad in order for you to get paid for that click, unlike popups, popunders and layered ads which pay for x amount of impressions.
I dont think thats any problem though if you have a couple hundred visitors a day. X% of them will make a click. I usually get 10 clicks per 150 or so visitors.
If anyone is wondering too adsense pays by keywords by waht adwords users bid on so
The CPC you'll get depends on your niche. If if have a MSRS (myspace resource site) you'll get like 1-3 cents a click

If you site if about electronics you might get 50 cents a click.
Check out
https://adwords.google.com/select/KeywordToolExternal tells the bidding pricing for keywords. (You have to put the Selection on "show Estimated CPC (cost per click)