For many years daisy chains angers have been a pariah in the climbing world due to weakness across the stitching of loops if incorrectly shortened. When used correctly they're perfectly safe and more to the point damn useful in an Aid-Climbing environment but the point remains if you use them badly they can fail catastrophically as shown in the Black Diamond testing video below:
Fortunately there a couple of new products on the market that help mitigate these risks, the most recent of which the CAMP Daisy Chain Twist that we've just received into the shop which uses an innovative twisted wrap to ensure that you can never clip across just the stitching of loops. As with most daisy chain designs they are still to be used in bodyweight only situations.
The other alternative that has been around for a while is the Metolius PAS (Personal Anchor System) which uses loops of triple overlapped webbing to produce a chain. Again there is no risk of clipping incorrectly as every loop is full strength and clipping any variations of loops maintains this. The advantage of the PAS is it's ability to be used in full strength applications, for example to belay from on multipitch climbs (hence the name!).