I didn't miss d-rings since I had never had them. I just purchased more quick links and attached them to the loops and used this like a d-ring. Never had a problem. Even used it when I started carrying a pony.I actually have both an Islander and a TravelPac, which I use for recreational trips....light weight, easy to pack, don't raise eyebrows in oddball locations.
I used to travel with an aluminum backplate and small wing; some real advantages for configuration.
You will probably need to carry weights; if you prefer integrated, that is a bit of a messy and expensive issue with the TravelPac and a BP/W, because you have to purchase and install weight pouches. The Islander is easy, because it has weight pockets. The Islander doesn't have D-rings, and I love my D-rings for lights, regs, ponys, misc. So now I use the TravelPac, with added weight pockets, and can step up to the BP/W if needed.
The advantage of the Islander, or similar back inflate, over the Travelpac is that it does have integrated weights and pockets, small pockets but large enough for a backup light or similar item. I think it is a good compromise for anyone that likes simplicity and minimal restriction but not ready to go the BPW route.
I haven't dove my Islander once since I switched but haven't been able to bring myself to sell it. It still hangs in my closet. Too many good memories to let it go just yet.