I got to experience Avatar Land and found it to be fantastically detailed. During the day the floating rocks were the main draw, at night everything changes and the whole area is beautiful to look at and amazing to explore. It's not the largest land in terms of the number of walkways through it, but there a lot of hidden things especially during the evening.
I really liked both rides. River Journey is short and sweet. I was glad to be able to get a fast pass for this as the queue seemed to just be a cattle pen. The final animatronic still made me think it was an actor, whilst there are little floating jellyfish things which mesmerised me throughout.
Flight of Passage was spectacular. It often had very long queues, with the longest I saw being stated as 210 minutes! I went in when the queue time was 95 minutes and for me that was a reasonable queue length, given the uniquely themed and detailed queue line, which could be an attraction on its own. I would say the queue line is perhaps the most detailed walk through Disney have ever produced. You go through five vastly different environments with about eight different scenes, each looking incredibly natural and as if it actually exists, rather than just being a queue line with some props.
The ride itself maintains this heavy attention to detail, wonderfully simulating riding on a Banshee. I had the biggest smile throughout, it was awe inspiring, even if the step taken from other similar attractions is perhaps not that great.
Getting a fast pass for Flight of Passage is incredibly difficult, and whilst it could save you a lot of queuing, you would end up missing all of the queue line experience. This is one attraction where I would really recommend experiencing the queue even if you get a fast pass, so long as the queue is no more than 90 minutes!
And some spoilers for those interested in the ride system.
The ride system barely moves, but you feel completely like you're flying from the wind and mist effects, plus the incredibly high resolution screen. Oh and the seat 'breathes', inflating and deflating by your knees, really making you feel like you're sat on a living animal. The ride seat has various little details, like a camera and screen you can lean forward and look at before the ride starts and it will show you being linked with your Avatar. The scale of the show building is surprising, as people are all riding at the same time over three floors and maybe four bays of 8 per floor.