With Love, I see him as clearly one of the top 5 players in the league. And I care about defense. I think he can be at least average and that's fine. Like Kevin says, he's so good elsewhere that its kind of obsessing over a weakness and ignoring everything else positive.
I think you could have easily said everything about Love's defense you would have said about Pierce before KG, for example. He stepped his game up. I think Love can as well.
In the end, Cleveland will have a lot of the weaknesses Miami had (mainly lack of depth inside, shotblocking, legit size). They will have LeBron and Love (two top 5 players) and Kyrie a step down (in the Bosh role). All the pieces fit better on offense than Miami did for sure. I could see this team being a juggernaut on offense.
The defense from the stars will not be on the level of Miami (Kyrie is no Wade) but if they fill out the team well they should be fine. Varejao and Marion are great pieces around those players to do that.
All this being said, I do like Chicago but so much depends on Rose. Either way they will be very good though I think with Noah and Gasol. That will be a dominant combo.