The downsides of wires are limited tire choice, tough to clean, and very few experts to true them to keep them perfectly round.
The upsides are: nicer looks, stronger than standard steel disc wheels and higher resale value (but if you're spending $1500 to put them on, then it's a wash!)
As for the change, it's actually very easy.
You'll just need a conversion kit, which contains 4 wire wheel adapters (which just bolt to the hub,) knock-offs and sometimes it will contain (depending on vendor) new/shorter wheel studs. If it doesn't, you'll just need to saw your current wheel studs down by 9mm (according to Bill Piggott) to clear the wheels. You'll also need new 11/16th in bolts to secure the wire wheel adapters to the hubs.
Or you can simply use 9mm spacers between the drum/disk and wheel adapter.
That's it!