I'd argue that it's in your best interest to have an agent. Two main reasons for this:
1. Contacts. Agents know which editor from which house is looking for what manuscript, when, and for how much. Agents do the networking and the submissions for you. Some publishers won't accept non-agented submissions (although this is less the case in romance than in, I believe, any other genre of fiction).
2. Contracts. It's more than just having someone legal-savvy to negotiate for you. If you don't have an agent, most likely you're getting a boilerplate contract from a publisher. Many agencies have already negotiated beyond this point and have a different boilerplate with that publisher, one that's already in the author's favor. So you'd be starting at an advantage -- and that's before negotiations even begin.
What's more, a good agent, one who really gets your work and is your staunch supporter, is a business partner. As someone at my local RWA meeting said this weekend, your editor is in it for the book. Your agent is in it for your career.
Does this mean that you MUST have an agent? No. There are many talented authors (hi, Susan!) who are very successful without having an agent. But I do firmly believe that having the RIGHT agent for you (which goes beyond having the right agent for your work) can be crucial to your career as an author.