Today is OnePlus' first birthday. There's a lot to celebrate, especially considering that the startup was able to launch a smartphone that was arguably one of the best of 2014. To do so, OnePlus co-founder Carl Pei offered some insight into the company and what he has learned over the past year.

"As you all know, since the inception of OnePlus, we have enjoyed successes but also experienced roadbumps," he said. "As is usually the case, we kept learning while moving forward, and are a lot wiser now than a year ago."

Pei offered some lessons, too, suggesting that startups should be confident, but "open up when you're wrong," and that you should always know the problem that they're setting out to solve. He also suggested you should always keep fans — and probably competitors — guessing, and said that there are "big surprises" coming in 2015.

OnePlus is also celebrating its birthday with a new $15 Power Bank, a 10,000mAh battery pack that you'll be able to purchase directly from OnePlus in black or white soon. Hit the source for a link to the battery and to read Pei's full comments.

Finally, if you've been waiting to buy a OnePlus One and haven't had luck through the invitation program or through open sales, the company said that the OnePlus One is once again now available for all to purchase while supplies last.