This holiday shopping season, more consumers are armed and ready with mobile shopping apps.

As smartphones have become more popular, nearly half of all users had tried shopping apps by midyear 2012, according to a Nielsen study. About 45 million smartphone owners used commerce apps, accessing those apps an average of 17 times in June.

Who are the shoppers most likely to download mobile shopping apps? “They’re a younger demographic that’s tech-savvy and comfortable using their smartphones for purchases, and they’re value-focused,” said Jason Buechel, senior executive in Accenture’s Retail Practice.

App designers are helping fuel the demand by constantly refining their products to make them more user-friendly.

“Early mobile e-commerce sites simply replicated existing shopping sites, resizing them to fit smartphone screens,” said Stephen Strauss, senior manager of PayPal Mobile Solutions, in a company report. PayPal is one of the companies looking to cash in on the growth of shopping via mobile apps.

Some retailers initially introduced apps that were overly complicated or tried to do too much. “Now, in ‘Version 2.0’ of their mobile site or app, you’re seeing better focus on the features that matter most to consumers,” Strauss said.

That includes simplicity and speed from start to finish, but especially at checkout and payment.

Other app developers are teaming up with sites to entice shoppers to make the transition from browsing to buying on their smartphones.

In its third incarnation, Black Flyday 3.0, an app that allows users to share through Facebook daily deals they spot, partnered with Monster Offers, a shopping site that aggregates local promotions and discounts, said Ryan Foland, chief operating officer for app company Iconosys Inc.