We highly recommend OneStepCheckout for all Magento store
owners. OneStepCheckout is the new must have Magento extension
that is taking the market by storm.

OSC is a total revamp of the standard checkout process in
Magento. The core feature is that it reduces the six standard
Magento checkout steps down to one. Totals and prices are
dynamically updated via AJAX when shipping/payment method is
selected. The user simply fills in their address and chooses
delivery/payment methods on the same page, rather than having
to do a separate step for each.

Improving the checkout process results in more customers
completing their sales, and this has an immediate impact on
your bottom line. It is the single most effective technical
change you can make to reduce shopping cart abandonment.

OneStepCheckout process. One step to completion.

OneStepCheckout simplifies the checkout process of your Magento
store. Checking out is often the most complicated part of
placing an order online, and many users end up abandoning their
order. Some customers will be motivated enough to purchase
regardless of how difficult it is – but others will be lost due
to check-out complexity. OneStepCheckout greatly simplifies
this process, leading to an immediate increase in sales.