Sorry for the late reply;
Bell's intro video to Fibe TV effectively sums up the basics (and just the basics) about what makes Fibe TV vastly superior to Illico NG.
Now, I can add that from my own use of Fibe TV and Fibe Internet (at friend's) I can say this, unequivocally:
Fibe TV is faster and more fluid. There is very little interface lag and the transitions are smooth. Illico 2.0 is slow and choppy. Navigating through menus is delayed and frustrating. Managing the PVR takes forever, frequently taking at up to 3 seconds before responding. Fibe TV does not suffer this.
Record more than 2 channels at a time. Can't do this on Illico.
Huge and fluid VOD. As noted with Illico as a whole, VOD on Illico is slow. So slow in fact that I stopped trying to use it because trying to find what you want took forever, is poorly organized and has a crappy selection. The experience on Fibe is smooth and seamless and there are actually movies to choose from!
Hugely superior interface. Aside from the noted slowness and fluidity issues, the interface on Fibe is more useful and easy to use. You can see more channels at a time, you can more easily preview channels while scrolling (without using the guide). The Guide itself is better with the way it presents information. Also, and this has long been a gripe with Videotron's guide, the Bell guide is ACCURATE. It can distinguish between new and old episodes and will TELL YOU what's new. The PVR on Illico can make the distinction, however you will never know what episode is new just by looking at the guide. Program descriptions with Bell are also complete and accurate (as in, it tells me about the show and the info is right); only (some) first run shows on Illico get useful program descriptions and good luck if that information is present in the future). I hate the generic 'tells you nothing' descriptions on Illico. I see far few of those on Fibe.
You can still listen to what you're watching when in other menus. I hate this about Illico. When I go to the PVR everything stops. Sometimes I just want to browse without stopping my show. With Illico when you go into the PVR menu all sound and TV is lost until you exit. Not the case with Fibe.
Channel content. Fibe's English HD offering puts Videotron to shame. Regardless of the reasons, Fibe TV has had a superior channel selection since day 1.
Price. My friends pay roughly the same as I do (we both have long term discounts), but they get TMN/HBO/AMC/FX; my bill lowered closer to theirs AFTER I cancelled those options on Illico and they get more internet bandwidth and more channels. They only have two services with Bell and I only have two services with Videotron.
Fibe TV is a lot like the TV services offered in the US (I have a lot of experience with Dish as well). US TV is years ahead of Canada and Fibe is the closest service to offer anything like the joys available in the US, both in interface and options but also in content (as much as can be done in Canada).