TC is fine for WiFi backups
If all you want is Time Machine backups over WiFi and you don't have that much data on a single Mac you will do fine with Apple's Time Capsule.
That said, if you look at your data storage needs and decide you want more then listen to the others about looking at a NAS. Especially true since you have multiple Macs and will strip thru Apple's 2-3TB of space down the road.
The biggest issues with Time Capsule is: No data encryption, no protection for your backup if TC drive fails and no ability to easily upgrade your TC (you can connect an external drive, but you can't bridge the data across volumes).
If wrote a rant about Time Capsule on my blog, but all in all for first time backup users it is a great way to get started. The real issue is that most folks quickly outgrow it.