No, the film makes perfect sense.
Obi Wan's goal in ANH was NOT to tell Luke the truth, but to convince Luke to go fight Vader. Of course he could not tell him about Vader being Luke's father, or anything bad about Anakin at all.
Not to say that he wasn't being honest at all before revealing himself. It fits his character even in ANH. Nor did he even bring up Anakin's name before Vader.
You can say that Leia being his sister is a bit odd, but it's far from a plot hole.