I have liked Tumblr from the moment I started using the service. The main selling points being able to customize the look of your blog to using using a custom domain names. Both for free (WordPress.com charge you for both). You can put your own ads, whatever pleases you.
I have constantly defended Tumblr versus its closest rival Posterous in the Tumblelogging arena.
But a lot of criticisms about the service have been raised. Up until now, except for Premium themes, Tumblr has no major revenue model, unlike other free but thriving online services. It’s not backed by a major online company, say like Google. So a question can always be raised about its sustainability. That’s on top of the fact that Mashable recently run a story about Tumblr getting a fresh investment.
Yesterday, Tumblr experienced a long downtime. I’m not particular with the actual length of time it was down, but it was real long by online services standard. It must have been at least 12 hours. This further puts a question on the ability of the company to actually keep up with this type of problems.
Another thing, I noticed lately that there has been a lot of spam blogs and spam Tumblr users liking or reblogging my posts. Same question: How would Tumblr Staff keep up with this to avoid or even eliminate spam registrations and blogs. Good thing Tumblr has no built-in commenting system. I can’t imagine further how would they respond.
So if you are a Tumblr user, you aren’t even worried about the future of your Tumblr blog?