Google Reader integration - not sure why they introduced a dumb feature called "Sparks" - it doesn't sound good - not sure where it populates all the content from either, would have loved to see my RSS feeds from Reader there instead of having to add interests
Ease of migration - it took me 2 weeks to get to G+ after all the fanfare in the media and other users; I was in no mood to create circles for each of my friends and start off my social profile from scratch. It's a painstaking process and just because it's drag-and-drop it doesn't make things easy for me. How about having an ability to add all my friends to a common open circle as soon as I share something?
More than anything else, I hate that G+ has not integrated already-available-fantastic-services to G+ such as: your videos from YouTube if you have an account there, all my Google Buzz posts - directly in my stream - not the way they have put it!
