The first thing to say about T-4 is that, for good or bad, it breaks the straightforward Terminator mould in which a target is hunted by a Terminator and protected by a guardian from beginning to end. Varied elements of this remain but that absolute pattern which remained unchanged from T-1 to T-3 is gone, and that might disappoint a lot of fans. I found the change refreshing, and the film has plenty of twists and turns from beginning to end, but the old trilogy is gone now, and often it feels much more like an extension into a new incarnation of the franchise rather than a sequel.
On the negative side, the acting is not uniformly great; I am not a big fan of Christian Bale, and would have loved to see Nick Stahl reprise his role from T-3. Most of the minor characters turn in fairly bland performances too. Anton Yelchin on the other hand is not just a good actor but an excellent mimic; it is absolutely obvious that he is Kyle Reese from the first moment he opens his mouth. He has captured Michael Biehn's range of facial and vocal expressions stunningly well.
The film has also attracted criticism for inconsistencies in the plot. Most of these will wash over you if you are watching to enjoy rather than criticise. It irritated me a little that the resistance seem much better equipped and situated than in Kyle Reese's memories from T-1; but perhaps over the course of this new trilogy that gap will close through losses to the machines as he approaches the age he was then.
Technically the film gets the full 5 stars for the DTS HD Master Audio soundtrack, great effects and pulsating traditional Terminator music (including 'You Could Be Mine'!) and unlike in "Public Enemies" the sound and dialogue are properly balanced. Visually the film clearly can tap great resources of sharpness and depth, but these are dispensed miserly at times given the grim post-apocalyptic look the director has gone for. Perfect reference shots in Full HD are not always aesthetically right for a director. The quality is there, but not always on show, and never flaunted, unless in some of the close-ups on Worthington fairly late on. Colours and contrasts are also usually very good, if one takes into account the generally grimy look cultivated.
On the cover it says "extended version", but this means you have a choice between the theatrical AND extended version; I would have to say I preferred the latter since I couldn't find any material which really seemed deserving of cutting, and the film, if anything, still seems a bit on the short side given the amount of ground covered. Other extras include good, if somewhat short, documentaries on everything from making the Moto-terminators and the Terminator factory to the work done for the "Return of an Icon" - if I say what this means it could be spoiler-ish! My only extras gripe: only one movie trailer and that for T-3! There is a leaflet advert for "District 9" in the box, how about a trailer on the disc?
One final technical note is that some have reported disc problems. I can report that the Sony BDP S 350 will play it based on factory settings having never been updated! And my 5000 ES updated Spring 2009 also plays it and loaded very quickly.
I think the film is a clear recommendation. It is a satisfying new beginning for the Terminator series (wait until you unexpectedly sight an old friend!) But it falls short of five stars due to too much bland acting, too much weak dialogue, and the eventual snowball effect of a few too many liberties and inconsistencies with previous Terminator history. Nevertheless, roll on T-5!