Straight into my observations and opinions:

• Cost: The PPP on this set is excellent, assuming that you pick it up at the MSRP or thereabouts. That being said, I don't see that there are any particularly rare/valuable/interesting bricks and there are a lot of little 1x1 pieces. Since I don't buy sets for MOCing it isn't a big issue for me. I will note that this is the first time I've seen the little frog piece, which really is quite cute.

• The various builds: I've only built the "advanced" build as the other easy/medium build versions simply didn't look all that interesting to me. That's just my opinion though. The advanced build isn't particularly difficult or time-consuming. The ladder, as MaartenRF10, is a nice touch. Otherwise, this is fairly straight-forward as builds go.

• The final product/appearance: The biggest issue with this set is a combination of the tree/house as fellow reviewer MaartenRF10 noted. My opinion on this is that the "house" is, perhaps, a bit fancy... and somewhat exposed to the elements. The other issue is that the tree has been, at best, defoliated. However, this isn't exactly a surprise - the pictures all clearly show the tree. I do believe that it wouldn't have been difficult or expensive for LEGO to have added some of the "Limb Element" (http://www.brickset.com/parts/?part=241728) pieces, which would have dressed this up a bit. However, there's no reason that a handful of these couldn't be added to the completed advanced version build. As it is, without any additions, the advanced version of the Tree House is acceptably good-looking. I should note that the size of the set and the "house" in the tree are at least in proportion to "real life" analogues.

• Playability: it's pretty good with this set as both reviewers Limpfittz and MaartenRF10 have noted. If you combined this with the Log Cabin set (http://www.brickset.com/detail/?set=5766-1) I think you'd really have something. Nonetheless, on its own, it's not bad. However, with just one minifig it's tougher than it should be - I think a second or third minifig makes this a bit more fun and compelling.

If you have other houses, in particular the Log Cabin (5766), I think this is a good set to get - they compliment each other quite nicely. Otherwise, on its own, it's ok but I'd recommend at least a few additional minifigs - any children minifigs from other sets, or one of the collectible minifigs such as 8831-10 Jungle Boy (http://www.brickset.com/detail/?set=8831-10).

I would say that this set is most for playing with, and I think many younger ones will favorite this. As an AFOL this is mostly parts for me, but I sure had a good time building it!

Pros

• Fun to build!
• Looks good, and playable

Cons

• the building instructions are extremely hard to read due to lack of color difference between browns, and dark browns.

Looks
Let's start with the looks. When I think of a tree house, I think of a tree. In that tree there's a small wooden structure built by a kids parent to play in. This Lego Tree House is not quiet like that. It's actually a house in a tree. The house is white, has actual windows and even roof tiles. I love tree houses, but this is not what I'd call a tree house.

Building
Building the main structure is rather enjoyable. It consist of a tree and a house, giving you two different things to build. There's some nice building techniques like the drop-down ladder. The other two buildings options of this set have less to offer. Especially the "easy-building" structure is very boring. It's mostly just putting a lot of small tiles on the ground plate...The "medium-building" has some foundations and a funny kitchen with an oven to put the pizza in.

Playing
This set is really made to play with. There's several things that can move. A ladder that can be let down and pulled up, a bucket on a rope, a little car for the minifig to pull, and movable branch to hide the treasure map beneath.

Pros

• High playability
  
• Lots of moving parts
  

Cons

• It's a house in a tree, not a tree house
  

A set that is most enjoyed to play with. It will be a favourite for children. The looks are not that good, so it's not the best piece to fit in your Lego village.