This book is worth reading once, I guess?  Nothing special really happens.  I don’t really see how any of this is tied into the whole Battle For The Cowl arc rather then the fact that it takes place in the same timeframe as everything else that’s going on.  I can’t even remember the last time Mister Freeze made an appearance in a Batman story.  They should’ve just left him on the back burner until they could think of a really good story to put him in. 
No need to run out and get this one, just wait until it’s in a $.50 bin one day.  I don’t see how any of the tie ins to Battle Of The Cowl have actually been the least bit relevant yet.  If you’re strapped for cash, definitely no need to spend it here.  If you are really looking for a decent tie in to hold you over until the day when Battle For The Cowl #2 comes in, go with the Azreal one.