So I'm finally ready to step up and become a DS user. 
I adored my Gameboy SP and after years of gaming focus given to my consoles I'm excited to jump back into the handheld market. 
 
But alas, I am gifted with a wonderful curse of being left-handed.  
I know the DS has modes for left handed users but I was wondering does it lessen the experience, or can I dive right in and not skip a beat?

Dive right in :)
 
I'm a lefty as well and I've never had issues with DS games,they all support and work well for lefties

The DS is one of the few consoles ever made that actually treats left handed users with any decency.

I have never had any problems.

Every once in a while I run into a game where being left handed is a minor inconvenience (the recent pokemon games are, shockingly, an example, thanks to the quickitem buttons being on the right) but its hardly an issue in nearly any game.