I’m a little confused – ‘exclusive’ usually means worldwide and forever, and almost always entails giving up all the copyright. You’re lucky to get more than just the writer’s share in any deal these days. By the sounds of it, you’re either getting 75% of the publishing, or 50% (if they’re saying they get 25% of all the royalties).
It’s always worthwhile getting an entertainment lawyer to look over the contract, however a good one over here will charge you several hundred dollars an hour. Depending on how long they take to look over the contract and how much re-wrting / negotiating they end up doing for you, it could add up to a lot.