I think having an RSS feed is a good idea. With one, readers can subscribe to your entries and keep themselves updated on your entries without having to actually visit your site to read them. And, because RSS is becoming such a mainstream feature of blogs these days, I feel that having a feed shows that you’re dedicated to blogging, insomuch as you feel you’ll be writing entries with enough substance and often enough that readers should subscribe to keep up with you.
The only downside that I could see to having an RSS feed is possible bandwidth problems. If a bunch of your subscribers have their readers set to check for updates very often, your site might get overwhelmed by the constant queries to the RSS feed.