CloudFlare offers a free plan with basic DDoS protection and promises to always provide a free service with at least the feature set that it has today. More advanced DDoS protection is available for the higher plans, which can be added as your needs grow.
Https ("secure") comunications with sites using CloudFlare are intercepted at their servers, decrypted and recrypted with CloudFlare's certificates. This poses huge problem with what users perceive as safe communication - browsers fail to display notice about MitM taking place.
Akami's services cost more than triple comparative packages from other security companies. At 13k a month for DDoS protection, there are many other choices out there that cost less for the same protection.
Not suitable if you have an association with online advertising. A single email that may include your domain that appears on Spamcop will result in a threat to terminate your account and a requirement to disable the URL -- even if you are not responsible for the production or sending of the email.