This depends on your location, and your droplet location, and actually a lot more things. I was wondering the same as you, so I just got one to test it and I am pretty satisfied, but I have been testing for just two days.

The page generation time for vanilla Wordpress (no plugins) is 250-350ms. (This is the time for generation only, no network latency, on CentOS 6, PHP 5.3, Apache)

With a lot of plugins (I run approx. 25-30/site) I'm hitting about ~800-1000ms for page generation.
However, you can of course cache static pages (with caching plugin) to serve them much faster.

It really depends on the latency between your droplet and visitors, how many visitors your site gets, and how many plugins/themes you have. I suggest trying out a droplet for a few days and seeing if it fits you :]

@santz: Would you mind testing it out yourself? There's currently a promo for a free month on their 512MB droplet (I can't find the promo code in my e-mail, right now, but I'm sure you could find it on Google or on DigitalOcean's Twitter feed).

According to D.O.'s FAQs, they use "Intel Hex-Core" processors and all of their "CPUs are b/w 2 and 3 GHz." That, coupled w/SSD drives & a Tier 1 data center ... I'd say their resources are sufficient for "a small freelancer's site."