Ok, I finally got round to watching them all. On the whole, they're a pretty good job. Pretty seamless editing, using the complete recordings, EE, etc.
- Books I and II (FOTR) are good. Not much is lost overall (I believe it still reaches over 3).
- Books III and IV suffer a bit, because most of the TT is pretty uncanonical. So there are some pacing issues, and they're not really satisfying to watch separately.
- V and VI are also short (even shorter, in fact), but even so, they seem to flow better.
General comments:
- Almost all the Gimli jokes are cut, so he becomes a pretty serious character, but some of the enemy-to-friend banter feeling between him and Legolas is lost because of this.
- Narrative is split more like book, so III-V only follow one group each, intro is moved, etc.
- There are some awkward cuts in an attempt to make it more book-like. Sometimes they work, sometimes they don't.
- Most of moany (and therefore most of) Elrond is cut.
- No Saruman Uruk-Hai spawning from mud.
- Far less Saruman scenes, but at least his final scene appears.
- The EE flet-scene is gone, which I thought was kind of a pointless cut.
- Faramir doesn't really get tempted by ring- but is therefore cut a bit too much for us to feel anything. I think that keeping the Boromir/Faramir flashback scene may have been useful.
- Denethor gets very very cut, but is far more canonical.
- There are some sneaky/clever edits to avoid some scenes, but I'll leave those as a surprise.
All in all, very good. Though I'd recommend that if you have 7ish hours, you should watch it all in one go the first time.