As MadonnasManOne said, it's been discussed in the 2006 Year of Superman thread.
I was thinking the same thing originally, to just wait until the Warner release came out, hoping it'd carry the AB extras and some new ones (like a Helen Slater commentary, or even just a 10-minute retrospective). Instead, WB is only releasing it as a little-more-than-barebones edition with the 125-minute version, commentary (from the AB disc), and trailer.
When I found that out, I hunted for the AB 2-disc set and was able to get one from e-bay for $65. Sounds like a bit much, but it's better than some of the going prices I've seen for the set (as much as $100 at times). Yeah, it's gotten that rare.
I wrote a quick mini-review in the 2006Supes thread, which I'm copying here:

(International Cut on left, Director's Cut on right)
-Video Quality: The International Cut is THX certified and is of really good quality. Wouldn't go so far as to call it amazing, but it's remarkably crisp and the colors are sharp. The Director's Cut isn't quite as good looking as the International Cut, it looks a little old. But is equally impressive, though the colors are way off/different, and the framing is pulled back a bit.
-Audio Quality: Don't really have an ear for this, but watching it on my TV and on my laptop in the various channels (well, 3. commentary, 2.0 and 5.1), it's a pretty even mix. I love listening to it on my laptop, though. Makes the Goldsmith score even more powerful.
-Audio Commentary - I've got a love/hate relationship with commentaries as some can be very well done (Katherine Orrison's commentary for The Ten Commandments is always worth listening to), while others are just...well, you wonder why they bothered as it offers nothing special. The Swarcz/Bosco commentary has a lot of great information about the film, and since it was newly recorded, there's very little that was repeated in the making-of.
-Making of Documentary - a nearly 50-minute documentary filmed during shooting, it's perhaps one of the best I've seen. You've got great interviews shot on-set and elsewhere, and wonderful behind the scenes footage (including Slater's screen tests). Sometimes the clips from the film can get a bit lengthy, but otherwise, this is a great addition and should've been included in the WB Supergirl DVD.
*Note - this, like the Superman 1, 2, and 3 TV docs, were produced by the Salkinds, so should have been part of the whole package of material that WB acquired when it bought back all Salkind stuff for the Supes DVDs. It's a damn shame that they didn't include this with Supergirl, but included the other docs with the first three films.
-Trailers and TV Spots - I've got a soft spot for these and have got to say, they really do a good job of promoting the film. It makes it more exciting and fun that it really is, which is a good thing, considering the fact that I entered the film with low expectations and found myself loving it. I love that there's a variety of trailers too beyond just the US one. We've got a teaser (with the John Williams score from Superman), and 4 trailers (US, International, UK, and German). And wonderfully, they're all 16:9 (oddly, except the German, which is fullframe)!
-Still Galleries - 4 different galleries with lots of photos. I'm not that big a fan of still galleries. They're interesting to browse through, but ultimately I like watching video footage over photos.
-Storyboards - next to the documentary, probably my favorite bonus feature as it offers storyboard montages for six sequences, all set to the Jerry Goldsmith score. Wonderful inclusion to the set.
-Talent Bios - standard information and filmographies, nothing really special but nice to read.
-Booklet - It's got a nice introduction and essay from Bosco and a quick breakdown of each castmember. Also, there's a poster and some press materials included which are amusing, but I didn't really see the need to. Also has the chapter listings.
Escapay