Your first conversation on a date with a new woman should be fun and intriguing, not consumed with emotional baggage and especially not discussions about your ex.
Women view men that can't stop talking about their ex non-stop as having unresolved frustrations and pent-up bitterness. Most men who talk about their ex do so because they're still trying to analyze what led to the breakup and have problems rebuilding when a relationship ends. By constantly talking about your ex to a new woman, she may see you as just trying to make yourself appear as the victim or the "wronged party" With this state of mind, a man is more likely to steer the conversation with a new woman into more of a comparison checklist, i.e., "my ex wanted me to take her out to expensive restaurants every night--what do you think of that?"
When meeting new women, think about how to focus on what potentially good relationships you could have with them instead of boring your dates with stories of your ex. Although women appreciate a man who can genuinely show his emotions, remember--constantly talking about your ex-partners and messy breakups can make a very bad first impression and run her off in a hurry!