The downside? They’re expensive. Like, really expensive, depending on which one you get. Whether you really need one depends on your budget and how you’re going to be using your ball. For example, I use official match balls for practicing freekicks because they fly through the air really nicely. However, I don’t use them for training because if I lose my ball I’ll be set back $100-$300.
My friend and I were kicking a soccer ball around the front yard. It was maybe 2007 and I was getting ready to leave for a couple weeks on a trial. Trying to be cute, I tried a handling skill where I flipped the ball up behind my back and then kick it with my heel so it comes back over my head again. So I kicked the ball too hard, it goes out into the street, and a truck promptly runs it over.
Great replica soccer balls! My kids love them. So much so, they are waiting until the fall when their new season starts to "keep them nice." They are authentic Adidas, and even come with the FIFA reflective sticker to place once the ball is inflated. Side note: The balls do arrive flat, so make sure you have a good pump with separate gauge as not to over inflate.
On the other hand, replicas (sometimes called training balls or gliders) are designed to be just like the official match balls but are much cheaper. Their panels are often stitched rather than thermally-bonded and are made of a different material. However, they’re not necessarily less durable than official match balls. So, they’re the recommended option for most players. https://www.youtube.com/watch?v=j2Xn84L3Kcs