I wouldn't do it, but I hate not having total control of my servers. Not being able to edit my SOA record at DynDNS even makes me a bit twitchy. But I digress; I'm assuming you're talking about hosting a website only?
Someone will have a nameserver for your domain - your registrar? If so, you may be stuck with their email services unless you can change your MX records. Also, SSL certificates could pose a problem with CNAMEs depending on how you handle the CNAME and cert creation.
If this was just a landing page or a splash page, I'd say go for it. But if you're trying to build something around website, you're going to want more control sooner rather than later. If they have a no-contract option, that may be worth it.
Please remember, just because a condition may be obvious or common-sense to you, does not mean it is so for everyone:
SSL Certificate on CNAME
Does an SSL certificate work on CNAME'd urls?