Twitter’s advertising efforts worked well in Q4 2015, but the company is having trouble retaining users — much less enticing new ones.

Twitter announced its Q4 2015 results Wednesday, showing that not counting SMS Fast Followers, monthly Active Users (MAUs) declined from 307 million in Q3 to 305 million in Q4. Year-over-year, this is only a 6 percent increase.

However, Twitter’s shareholders letter is quick to point out that they’ve seen January monthly active user levels rise back to Q3 levels. Impressively, mobile MAUs represented about 80 percent of total MAUs.

As of the end of January, we’ve seen MAUs return to Q3 levels. Confident in continued growth with disciplined execution. #TWTR

— TwitterIR (@TwitterIR) February 10, 2016

Advertisers have been much happier with Twitter’s progression. The company reported a Q4 revenue of $710 million — a year-over-year increase of 48 percent. Overall in 2015, Twitter’s revenues exceeded $2.2 billion. Ad engagement is up 153 percent, showing that users are reacting well to ads — no small feat.

Another huge announcement for Twitter: the company now has more than 130,000 active advertisers, a 90 percent year-over-year jump. In its shareholder letter, Twitter talked about the growth among its small business sector:

We expect that SMB growth will continue as we improve our product, making it faster and easier to run campaigns and improve our direct response tools. We are also very pleased by the growth in active users of our Tweet Analytics Dashboard, where people can measure the performance of their organic Tweets and can choose to amplify that performance with our SMB ads product. In Q4, our Tweet Analytics dashboard had over 25 million active users, up 3x compared to Q3, creating a large and fast-growing pool of potential marketers to convert into SMB advertisers.

Still, arguably the most pressing problem facing Twitter is the stagnant user growth. In Q4, Twitter reported a total audience (taking into account MAUs and logged-out users) of 800 million. That means roughly 480 million people view Twitter content without logging in.

Through a sample experience on a log-out screen and an algorithmic Timeline setup, Twitter is bending over backwards to cater to users who are confused by the service.

In the shareholder letter, Twitter explained how they want to make the site easier and more intuitive to use:

Twitter is an iconic service and a globally recognized brand. We are going to fix the broken windows and confusing parts, like the .@name syntax and @reply rules, that we know inhibit usage and drive people away. We’re going to improve the timeline to make sure you see the best Tweets, while preserving the timeliness we are known for. The timeline improvement we announced just this morning has grown usage across the board (including Tweeting and Retweeting). We’re going to improve onboarding flows to make sure you easily find both your contacts and your interests. We’re going to make Tweeting faster while making Tweets more expressive with both text and visual media. We’re going to help people come together around a particular topic, such as our @NBA timelines experiences. Relentlessly refining Twitter will enable more people to get more out of Twitter faster.

Readers: How can Twitter make the site easier to use — without alienating core users?

Top image courtesy of Ellica / Shutterstock.com.