ObiWanKennerobi said:

We know Anakin was a great guy because Alec Guinness can actually act. When he says "and a good friend" it is said with such a glowing genuine warmth and wistful nostalgia, it simply couldn't have been any other way.

Everyone argues with their good friends.

I think the main problem I have with the Obi-Wan/Anakin friendship is that Anakin is portrayed as a completely unlikable person (they made him WAY too angry and murderous in Attack of the Clones), and they didn't show enough of Obi-Wan and Anakin acting as friends for the audience to be able to look past the arguing. Maybe if they had acted like great friends from the start and then as the PT went on and Anakin started drifting towards the dark side they could've started arguing more and more, but Lucas never really emphasized their friendship in the first place.

As for what I like about the prequels, I like a couple of little things like Christopher Lee (even though that character was a completely wasted opportunity to make an interesting villain). Not much else though except for Ian McDiarmid's excellent portrayal of the Emperor, but even that wasn't enough to make up for how confusing and nonsensical the Emperor's plan was.