I recently helped a fried migrate from MT 2.61 to WP 1.2. Everything came over without a hitch, EXCEPT for some reason, some of her comments were out of whack. But considering she had three years' worth of blog entries, that was a small price to pay.
Several things you will likely love about WP over MT is (1) your files take up much less space. When I migrated a year ago, my blog occupied approximately 90MB of server space. Converted to WP, it slimmed down to just under 30MB. (2) The templates are easier to master. WP 1.5 has a few more templates because it is using a new template scheme, but even so, there isn't that daunting array of templates that there was in MT (MT had two site templates, three archive templates and four comment templates, not including templates you might have set up for your own uses). Contrast this with WP's 1 template (WP 1.2) or 4 templates (Main, Header, Footer, Sidebar) in WP 1.5.
Welcome!