You can grab the original Dead Space for free on Origin "for a limited time only"
If you've somehow managed to avoid grabbing Dead Space despite its numerous sales these past few years, you might be glad to hear that it's currently completely free to grab over at Origin. The promotion is set to last "for a limited time only", so I would recommend you go and get it as soon as possible since it's unknown when exactly the whole thing is going to end.
As for whether its worth your time, I would say the answer is a definitive yes. Dead Space 2 is personally my favorite of the series, but the original still has some great action and tense moments that make it well worth a playthrough. Even if you're not a fan of scary games I would still recommend you give it a try since Dead Space is more about atmosphere and immersion than straight up horror. After all, it's hard to be scared when you dismember your enemies with each strike!
If you're planning to use a mouse & keyboard combination for your playthrough, I would highly recommend you install the Mouse Fix patch. It will make Dead Space use raw mouse input without any additional smoothing or acceleration, so you won't have to deal with the fairly sluggish controls that come with the original version.
And finally, allow me to send you off with the most recent trailer from GOG. There isn't much gameplay on display, but it should get you into the right mood regardless. Enjoy!