Personally, I would LOVE for the show to look and feel like the LOTR trilogy. The world building is one of my favorite parts of those movies. But it's possible Amazon will have to start from scratch.
While I believe the show will be shooting in NZ, I don't believe Weta is involved. Not that I've read, anyway. So while the show may want to feel like an extension of the New Line/Warner Bros movies, there are legal reasons they may not be able to use the same designs that were created for those films. All the designs for clothing, armor, castles, creatures, etc. are property of NL/WB.
That said, it's possible they've made some kind of agreement that they just haven't told us about to use some of the same designs. That's what I'm hoping for. I believe John Howe may be involved with the show, the famed Tolkien illustrator who was one of the two main conceptual artists (along with Alan Lee) that worked on the Jackson movies. So that's a good sign. Fingers crossed...
John Howe is on board and the contract with Amazon includes the Tolkien estate, Harper Collins and New Line.