Twitter has expanded its $99 a month ad subscription program, called Twitter Promote Mode, to more accounts. Right now, the ad subscription program is targeted toward small businesses. While $99 sounds like a bargain for ads on a social media platform, there are a couple things to consider.

You don’t get to choose which tweets get promoted.

This may not be a huge drawback if you are disciplined about only posting relevant content to your Twitter account, since you can still use the regular Twitter ads feature. However, most people want control over how they are spending their money.

Another thing to keep in mind is that if one of your tweets is picked up by Twitter Promote Mode and you decide to promote it manually through the regular Twitter ads platform, Twitter will treat those posts as though they were two different campaigns.

You don’t get to choose how many tweets get promoted.

Participating Twitter accounts will receive “up to” the first original 10 tweets each day as Promoted Tweets. The good news is you don’t have to worry about retweets, quoted tweets, and replies counting toward your total. The bad news is that it’s highly unlikely you produce 10 posts of your best content in a row and that you want all those tweets promoted at the same time.

Your options for Twitter Promote Mode are limited.

With Twitter Promote Mode, you are only able to turn the service on and off. Your targeting is also limited to 5 interests or metro locations/regions in your selected country. Both are useful tools, but they still don’t provide enough control for most people’s liking.

Twitter doesn’t guarantee success.

It’s not surprising that Twitter won’t make promises about performance. That’s a standard disclaimer. All Twitter says is that an account enrolled in Twitter Promote Mode will on average reach 30,000 additional people and add 30 followers each month. This means that your account may see an increase less than the average, but you’re paying the same $99 as someone seeing more gains.

If Twitter ads appeals to you, proceed with caution because this may not be the best way to spend your advertising dollars. At least, Twitter allows Twitter Promote Mode users to cancel at any time, so you’re not stuck in a contract.