For starters, have a look at the Wikipedia article about it. I find this Wiki article balanced, albeit a touch too short. It's at
Ilyushin Il-18 - Wikipedia, the free encyclopedia.
When you look at Soviet-era aircraft, military or civilian, they are designed to be as low-tech as possible for (1) reliability and (2) ease of maintenance.
Nowadays, we would call it ergonomic, sustainable development-friendly or somesuch wordmix of the ilk. This means your concern is with the airline's adherence to accepted standards of maintenance and training, rather than the aircraft itself.
However, given its date of maiden flight is 4 July 1957 and that I have suffered about 1hr30min of a Tupolev 154, it may be rumbly and noisy so that you will arrive both shaken and stirred.
That said, like most SLF, you are terribly-terribly likely to survive. And may even disembark so proud of yourself that you will be able to spin a few dinner party anecdotes from the experience.
You can also check:
Aviation Safety Network > ASN Aviation Safety Database > Aircraft type index > Ilyushin 18 although it is not that user-firendly if you are trying to compare an aircraft type's safety with respect to other types. This is both dodgy and fair: lots depends on maintenance and crew training/skills.
At all events, unless my data is out of date, general wisdom has it that only rail travel is safer -- in some places at least.