I'm glad Twitter doubled their character limit.
I think it's a small improvement on a site that has a long way to go to arrive at anything resembling civil discourse. Moreover, I see no downside—to the extent that it "makes Twitter less Twitter", I think it's a good thing. It probably won't encourage me to stick around on Twitter much more than I already do, nor will it really change how I use the service, or (I expect) how anyone else uses it.
It doesn't solve any of the problems with violent extremism flourishing on the site, nor does it solve any of the other problems with misinformation spreading like wildfire (looking at you, Retweet button), or biased verification and moderation practices. It doesn't solve the problem that Twitter, as an organization, is too cowardly to kick off someone who makes violent threats (and has the capacity to carry them out). Nor does it come anywhere close to solving the tweetstorm problem.
But it does leave just a little more room for nuance. It gives people the opportunity to say more, and get closer to saying what they actually mean. And that can't be a bad thing.