I like it. Many novices are afraid of getting in close. They do things like close their eyes, tangle up their arms, push or constantly back up anytime they get too close. This is a natural instinct. Everyone is used to a certain degree of personal space, so rather than rely on their defense, beginners naturally want to back out and escape. So forcing them to face their fear and rely on their defense is a good way to build confidence on the inside.
One thing I will stress when using the tire. Make certain that boxers are well matched at weight. A heavier fighter has a huge advantage in this style of training. We regularly have Victor Bravo spar heavier fighters in and outside the tire but I would not recommend that for everyone. Victor fights at 126 - 130 but he regularly spars boxers from 140 to 155. He has even sparred several middleweights to heavyweights but not in the tire.