I had a bad experience with my last pair of GAM's. Factory defect. So nothing that's going to happen with every skate. Other than that, I've skated on GAM and loved them. Similar to Jackson in size. I find them a bit wider in the toes. Maybe a lower heel? Check out Kenzie's closet because they have size charts with the actual measurement in inches so you can check the length. I have only heard of a select few people saying they 'hate' GAM (I might have been one of them when I had warped skates
). In general, they're comfortable and good for kids. They didn't have a model in high enough stiffness in stock at the place I bought my last set of Jackson's at or I probably would have bought GAM again despite the problems I had.
Edit: in terms of breakdown (mentioned by Bill), as with any brand, it's important to make sure the skate is appropriate for your needs. GAM, like other brands, make a wide range of skates from rec all the way up to strong enough triples, quads, etc. Google the model number so you know what you're getting. GAM and Jackson broke down in a similar amount of time for me.