I made this for a picnic and it was quite delicious. The only problem was that I didn't put enough gelatine in and therefore it was not very stable. But it lasted well, and what was left was still delicious after 2 weeks. I don't get the previous review because you state specifically that it need to be made well in advance.
This is a good dish for the summer time because it's served cold and is light, but you'd do well to do the grilling while you're cooking hamburgers because you can't eat the dish until considerably later. It was a little time-consuming, but I found the taste to be quite yummy.