As a character herself Dawn was alright. Its just that I didn't like her character interaction with virtually everyone in DP. The characters she brought with her into the series, including Johanna, Piplup, Zoey/Kenny, etc. were all not very interesting in my opinion.
I think Dawn might have had more potential in her own series traveling by herself rather than being forced to travel with Ash/Brock in DP. In DP1 we see her perfectly capable of starting her journey by herself anyway.