I tried adsense and it took me 9 months to make $100.00...many people told me they made a few hundred a year - it was discouraging, but now I just look at it as bonus money in my paypal acct! The irony is that I never notice ads on other blogs!!
Blogging is a lot of work. If I put forth the effort to inform and entertain, I most certainly think it's fine to receive compensation. Some blogs have gone overboard with advertising, and they are difficult to read for all the flashing and what-not. I love the extra ca-ching I get from blogging and never mind anyone else having ads.
Go for it!