@themalteser, I've done this program and from my experience, I really enjoyed it and it absolutely packed on some quality mass. I had the same thoughts you had, when you're used to training frequently with a split routine, 3 days per week may seem like "not enough".
BUT, keeping in mind that you should be changing up your training programs every now and then, let's examine why a 3 day per week full body routine like this is awesome.
-RECOVERY - Most people who train significantly undervalue training. The whole point of training is to recover from training, you only grow when you're recovering. A 3 day split gives you ample recovery time. If you're not used to this much recovery time you'll be surprised how much you grow. If you've been training for 11 years and haven't changed up your training style yet, it's certainly time for some experimentation.
-Having every muscle stimulated during each workout, so 3x per week, will certainly keep you growing and will be more than "enough."
-The set/rep scheme involved in this program emphasizes both size and strength, so when you do hit your split routine again, you'll be bigger and stronger than you used to be and will be able to continue making new gains.
I've done a few different full body program over the years and am a big advocate for them. Training full body 3x per week is perfect for those on a tight schedule, or for a change of pace after running a split routine for a while. Remember that this program isn't a muscle group specialization program, like trying to build up shoulders or whatever. It's an overall mass program, and is also meant to be run while in a caloric surplus so you can put on the size you're working for. I highly recommend it! Follow the instructions in the article, give it a go for 6 weeks or so, eat up and see how you look when you're done.
Some quick advice for this program, be sure to warm up your body as you're working a full body program. A quick 5 min on the elliptical before you start, and any time you start a new muscle be sure to have a least a couple of warm up sets before your first working set.
Push yourself hard and load up big time on pre and intra workout carbs, Finibars and Plazma are ideal. Make sure you're eating to gain mass so the program can work as it's supposed to.
Any questions, be sure to post them!