The Vu Tower only damages Residential buildings. How many varies with the Level of your Vu tower and the type of disaster you launch but so does the reward i. e. a Level 7 Meteor III Attack damages 4 buildings but provides 3 Keys and 500 Semolions upon repair, while a Level 7 Alien Invasion I damages 2 buildings and returns 2 Keys no cash. Repair requirements are on par with the final upgrade of any building, they do designate the disaster repair requirements as Easy, Medium or Hard, I really can't tell much of a difference just a slight variance in the items needed Easy more Steel and Wood and Hard more Donuts etc.
You're definitely missing out on an important asset if you are not utilizing the Vu Tower. The only downside is collecting enough Vu Specialty Tokens which can be hard to find at times and an additional strain on your storage if you have not kept up with upgrading it. I try to keep at least 10 ea. of the 3 styles of tokens on hand at all times. The amount needed to launch an attack varies with disaster type and level. A level 7 Meteor III attack requires some combination of 5 Tokens, so you can see how quickly you can expend them.