Capcom announced today that Gyakuten Saiban 4 passed the half-million mark in shipped copies today, a new record for the series. It's no surprise that being on the DS boosted sales; it's likely to boost sales of anything. But let's not diminish the accomplishment. Gyakuten Saiban 4 is a hit!
This milestone has contributed strongly to another milestone: as of today, the Gyakuten Saiban (Phoenix Wright) series has shipped 2 million copies in Japan alone. That's pretty great for any series, much less a text adventure series! If there were any objections within Capcom about spending the money to localize GS4, they've probably been shot down by now.