I have been a loyal fan of Dragon Ball Z since I was younger and watching the original run on Toonami and on VHS. I drifted away from DBZ for many years but have been an anime enthusiast ever since DBZ got me hooked.
Dragon Ball Z Kai caught my eye for several reasons: mainly being remastered yet retaining the original 4:3 aspect ratio (unlike the previous two versions that chopped part of the format to be presented in pseudo widescreen). I have faithfully purchased the Kai series (the titles released so far) on Blu-Ray. Here are my thoughts:
This part takes us through the Trunks and Android sagas up to the Cell saga (can't wait for Sept 15th!)
The ratio is kept to the original 4:3 aspect. Some animations have been cleaned and even re-animated (in the case of some of the lighting effects from ki attacks and power-ups). Some of the re-animated shots look like something from American Saturday morning cartoons rather than anime, but these instances were very rare. The two that stood out were in the previous volume anyway.
The sound is vastly superior to the previous versions. The English dub is improved and they aren't afraid to get a little dirty (they swear often, but not in an offensive way. They just yell 'you bastard' a lot). Though the few uses of swearing is in line with the more literal translation. Also, the American voice acting is a lot better this time through. Most of the lines have been slightly changed to stick closer to the actual translation. The Japanese voice acting is the original (highly amusing in some roles) though it has also been cleaned up a bit so that static is removed.
The music is the original Japanese score, just re-digitized for this release. It is superior (quality) to the original Japanese (analog sound) and the American scores (though the American score was pretty good considering). (Clarification: the quality is superior in this release, the Japanese music being re-digitized and cleaned up and the voice acting both in Japanese and English has been redone is many parts. So when I say superior, I meant superior quality to the original)
Here is where most die hard Dragon Ball Z fans choke up: There is a lot of cut content. I have seen the original, un-cut, American and Japanese versions. I gotta tell you. You're not missing anything. Most of what was cut was pure filler by TOEI trying to fill time slots. They've also removed a lot of re-used cells. I remember how annoyed I was to see Piccolo battling the Android and TOEI reusing animation cells from the Piccolo-Raditz battle. Seriously. Also, I don't hear too many people upset about missing out on the Garlic Jr saga.
They cut about 50 episodes (give or take) and reduced the amount to 98 (through the Cell Games saga). I don't know if they will continue through the Buu saga (no word yet even in Japan), but I am a huge fan on the improvement in quality of picture and sound so I hope they do.
Also of note: the Blu-Ray version is presented in full HD, though the original show was analog and standard definition. There is a noticeable difference between the DVD and Blu-Ray version in animation clarity and quality. There is also a major difference on the sound. The difference is worth the $2 or so for the Blu-Ray vs DVD if you have a player.