Antispin is an inverted rubber that doesn't produce any spin. Normally if has one of this behaviors:

1 - Kill the ball's spin: These kind of rubbers produces effective stop block, drop sots, safe pushes and can be used to flat kill. More suited for attack, but not as effective (in my opinion) as an anti that....

2 - Leaves the ball spin freely as it came (a la long pips): These can produce effective chops and chop-blocks AND any stroke of the (1) anti kind, also they have more problems to hit against topspin or no spin, but can loop or hit against backspin with ease. More suited for defense than anti of the first kind. I like this kind much more than type (1).

Most antis, however, have an in-between behavior: They kill spin, unless they're used to continue the spin (stroke the ball in such a manner that, if the rubber was spiny, it would return a ball with the same rotation axis / spin direction that of the incoming ball). They offer some variation, and can be used for chopping, but they're not as effective as long pips.

Do NOT use anti (short pips are useless too) to cover your weak backhand. Get a slow inverted so you can improve your technique. I believe that anti should only be used in the case that you can take advantage of its properties and have a style that demands a high control rubber, such as blocking against loops at extreme placement. To play the spin reversal game, try some pips (specially chopping long pips).