The main problem is the ads/promoted tweets creeping in more and more.
I think the problem is now they are driven to maximize profits rather than being a great service for users.
Probably should have stayed private so they could balance making some profit with providing a great user experience.
$.10 for 30 more characters would be a huge benefit for Twitter.
For example: I used to keep an eye on Twitter during major product launches that would generate lots of traffic (namely, iPhone preorders). Some simple searches, refreshed every few minutes, would give me an idea as to how the launch was going and if the website stayed up. If anyone tweeted a problem, I forwarded that to the PR and customer support teams, so that person would get a response within minutes instead of potentially missing out on the preorder window. The ability to integrate something like that into a customer support ticketing system would be pretty awesome.
Out of sites like Facebook, YouTube, etc. etc. Twitter is the only one that, on a daily basis, makes me wish I could pay to not see their shitty ads.
With any advertising, the goal is for the advert to be shown to people who might be interested in it. If I hate sports and you show me an advert for football tickets, you've just wasted a tiny bit of that advertiser's budget because they will never make money from me. If I love football and you show me that ad, there's a chance that might be an ad impression that gives ROI.
I don't find the ads creepy at all, I find them absolutely irrelevant to me. And Twitter should have enough data about me - I've been talking about myself on there for years - to do better at guessing which adverts might interest me.
You might like sports, folk music and deers, but when reading a tweet about Donald Trump, you'll see ads for barbwire.