Here is the blurb from the website:
Alpha Strike is a new, fast-playing form of the BattleTech game of futuristic, armored combat. Developed for the modern tabletop miniatures wargamer, this book brings players the ability to wage war on land, sea, and air using the Quick-Strike game system first devised for truly large-scale play, re-scaled to the tactical level of “classic” BattleTech. Complete with sample armies and a ready-to-play campaign system, all you need besides this book are dice, miniatures, and tabletop terrain to fight for control over the Inner Sphere on land, sea, and air—one world at a time!
The preview shows that the final version will be over 155 pages including campaign rules and scenarios, scene setting for the Era the game is set in, background info on the Battletech universe, as well as the rules. The rules are split into introductory rules for a simple game (10 pages), the standard rules (27 pages) and a load of advanced options which cover 50 pages.
The preview contains eight pages of the Introductory rules, so not the complete set. It's hard to get a feel for what the full game will be like but the big change is obvious, damage allocation. Gone are the detailed record sheets like the one shown below.
These appear to be replaced with a much simpler record sheet about the size of an index card.
As can be seen there are only four states for Heat and the Armor and Stucture boxes are much reduced. Apparently info is provided for the various 'Mechs that you transcribe to the card. For example the preview mentions that a Capellan AWS-9M Awesome is rated at 8/4 meaning that you block out all but eight of the Armor boxes and four of the Structure boxes.
So the preview is interesting but not really playable and leaves a lot of questions unanswered. However the full rules will be available to pre-order on July 29th with the PDF version being only $15 so worth a punt.