I can't talk about the welfare optimising effects but it's a more efficient way to generate a similar outcome to a classic 'bid upwards' English auction - I assume you know the process of that.

Imagine we have four people competing, who each have a max bid of:

Alice: 100, Bob: 150, Charlie: 155, Diana: 180,

In a standard auction bidding would, say, start at 50. When the cost exceeded 100 Alice would drop out, similarly for Bob at 150, and Charlie at 155. So Diana would win and pay 155 (plus maybe one bid-increment, depending on who bid first).

So, if each simply submitted their max bid under the Vikrey auction rules, Diana would win, and pay 155. The whole bidding upwards process can be avoided, which is by some standard more efficient, and everyone pays essentially the same as they would under and English auction.