A large part of the reason I postponed reading on is the tone of the books. Somewhere around the end of the fourth book, the series is no longer a fantasy adventure series. Instead, there's Harry all Being Misunderstood by Parental Figures. I had real trouble getting through The Order of the Phoenix because most of it was just Harry moping around because he wasn't allowed to Do Things That He Feels He Must Do.
The adventure is gone, and it has switched into a mode of Serious Book Spanning Plot. Reading through OotP and tHBP was more of a chore than pleasurable.
Tell me, is the pay-off all worth it? Should I plod on? Will the adventure return?
Is the tone of Harry Potter and the Deathly Hallows as uninspiring as that of Order of the Phoenix and The Half-Blood Prince?
If you have anything else to add, feel free to leave a (non-spoilery) comment!