Yes!
While the Icelandic fermented shark is fervently disgusting in its own, interesting ways, I would think that most of us that are (un)lucky enough to have tried them both would say that surströmming is much worse.
I'll quote from
a comparison of the two, by Australian writer Demis Lyall-Wilson (quite a funny read):
Originally Posted by Demis Lyall-Wilson
There is no reason for people to feel they need to eat Surströmming at all, ever, for any reason. If I had to chose between eating Hákarl every day of my life or eating Surströmming one more time, I would still go with the daily shark.
The Swedes have this one completely sealed. There’s something truly horrendous about Hákarl that I don’t want to take away from our Icelandic friends – it *is* incredibly horrible, and I love the crazy way it’s prepared – but the fact that I walked into the Swedish sitting thinking it might be easier, only to be uncontrollably gagging within seconds of the can hissing its vile stench out into the world? No. Just, no.
Hákarl is definitely a 10-out-of-10 experience for people looking to expand their culinary horizons all the way down into the darkest depths of putrefied-shark depravity, and that’s fine. If you can get your hands on some, knock yourself out. Have a laugh with your friends. Brag about it, as I did, on Facebook. But know, deep in your heart of hearts, that while you just gulped down an ammonia-soaked 10-out-of-10, that just across the sea, there lurks an eleven…
There really are no words to describe it.
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Ragnar