The anime adaptation had the complete series to work with so it covers the material nicely though it does trim a lot of "in-betweens" out. The anime trims out some sidestories some of Risa's competition gets trimmed down.
But having watched the anime first and read the manga -- I've been quite happy and have gotten even more impressed with the anime's adaptation.
I'd say its was a bit like watching LOTR in the theatre and then getting to watch the extended version at home.
