The mechanism in as shown in the article (bring all the bags to the check-out lane, scan, weight, pay) is just horrid, and way slower. I just go to the regular checkout in these cases. I've seen a store which replaced all regular queues with self-checkout lanes, and now I just avoid it.
The second method is by taking a barcode gun with you at the entrance, scan the items as you go, and simply pay at the exit. There are random-rechecks, but they are performed by the cashier, so they're quick. On average, it's actually faster, and I do prefer this method. The barcode scanner takes the tally for you and can do a price check, which is another convenience to have sometimes.
Every store I've seen using this tech was from Siemens and I'm pretty happy about the implementation.