To be specific, I really loathed the fact that Tumblr would tell you how many minutes it was until a post would go live. So, if I had a post that was to go live a week from now the queue would read something like "This post will be published in 10,000 minutes.". That made it very difficult to schedule posts based on my desired schedule (twice or three times per day spaced out evenly).
Anyway, that gripe is now long gone. Thanks Tumblr.