This episode was really hard for me to rate.
I know the O6 etc didn't have a big part in this episode, but based on the title...I figured we were just going to follow Locke for a bit anyway. Get some answers. So I'm not disappointed that they didn't have more screen time. We had to get through his visiting a handful of people, and it was rushed, but this added a nice tension to Locke's mission: failure after failure. Then he despairs.
I like/dislike certain parts of it, but all those opinions are scattered over the forum, so I'll try to keep it short here.

I felt like the big check-list of all my questions was getting shorter: "Tunisia is where the exit is." Check! "No, I didn't know he killed himself." Whoa, check! "Widmore used to be the leader." Check!
The first few episodes this season, we've been getting boatloads of information. Like exploratory surgery: We know the story's there somewhere, we just have to get through a bunch of other stuff, probing, answering some questions on the way, until we arrive at the real meat of the story, the important stuff. In this episode, we got to reap the first of the many rewards of all that paying attention. Less explaining about time-travel and getting everyone together; more following these characters' journeys.
We've met the major players, and now we can sit back and enjoy their stories. This episode just opened up so many roads to answers, and for some reason, I felt like it is the
journey that is the most important. I feel like I can relax now.
So I'm basing my rating on staying true to the title, answering a couple of mysteries, Ben's general awesomeness and Locke's pitiable situation, the plane landing on the Hydra island (great twist), and setting up more mysteries and conflict (like Frank/possibly Sun not being in the same time as Hurley etc). There are parts I disliked, too, so it wasn't the best ever. But it still rocked.
9