Avatar will probably be the best indicator, If Avatar disappoints SWL will likely also.
Avatar will disappoint only in terms of the attractions on offer. Soarin 3.0 may not tickle everyone's fancy and the boat ride is going to be short unfortunately. The land itself will be the star and should blow us all away.
Fortunately, we've got a few things on our side for Star Wars Land in Florida.
Most importantly, it's a clone of what is going in Disneyland and the show quality banner is still high out west. It also is being given a budget that is allowing 2 E-ticket attractions along with the land. Both the Falcon and the Resistance/Battle/Adventure attraction should exceed the ambition of anything in Pandora.
Based on the concept art and the details that I know about the place, I'm not so sure that the land of Pandora won't end up being the better looking/more breathtaking of the two. It should be beautiful. That's not to say that Star Wars Land won't be, it just won't lend itself to being as panoramic and breathtaking as the floating mountains. Similar to Cars Land to Diagon Alley in appearance. Both at the top of their class in terms of what is possible in a theme park. One is awe inspiring in the vistas on display and the other is just as impressive in terms of the fine details (and also the vertical visual scope).
I mentioned in the Disneyland thread on this topic that I'm 100% satisfied based on what I know in the loss of what they are giving up to get what will be gained with SWL. As much as I hate losing all of Rivers of America, the opening of SWL will be well worth it.
Considering we're losing part of a parking lot and a stunt show in the swamps of Florida... it's no contest.
Also, just a reminder that NFL is just fine in its execution. It was the lack of ambition that ruined it. What we got out of it looks better than the limited scope dark ride, fancy meet-in-grope, smallish coaster, and dueling Dumbo's has any right in looking. I'd argue that the new stuff in MK looks too good for the rest of the park. It's really abrupt when you go to use the Tangled restrooms and then walk back into tent city. The "way" is still there at WDI... it's just the "will" in terms of the budget that limits the ambition.