Groupon: $20 for $40 voucher for G2000

Anyone has direct experience of using Groupon vouchers? I can see that businesses will have a tonne of customers from the offer. Wonder if they get their email addresses too.
Will businesses get swamped by too many customers at one go (or over a short period of time? I would be wary of getting vouchers from small-chain restaurants and spas and hair salons.

Wonder if anyone has experienced the service levels at service-biz? These guys are working on very thin margins and u wonder if they can keep up the smile and graciousness.

The Groupon offers I would think are safe are those biz involved in clothes (like G2000). Just go and pick up what you want.....

Today’s Groupon deal:

$338 for 4D3N Bali Kuta J Boutique Hotel Stay with Return Air Ticket (Worth $644)

today's Groupon deal --- $10 for $20 Worth of Thai Cuisine at E-Sarn Thai Corner at Thomson Ridge

$10 for $20 worth of Ice Cream at Ice Cream Chefs

Clinch the deal via the Groupon adverts

$25 for $50 Worth of Chinese Fare at Seafood Paradise...via Groupon

$19 for Sashimi Aori Set at Miz Japanese Restaurant (Worth $38)