If you are happy with slow growth then yes, it is a very safe investment and will rise this year. However, do not expect massive growth as it has already been to the moon. You should invest in cheaper coins that will reach the same price as ethereum. Take a look at LISK and NEO, both of which are competitors to ethereum and will rise rapidly this year. LISK is cheaper, but NEO is already ready with ICOs - both are better investments for 2018
That's the thing about Ethereum. It is stable and reliable, but on the down side, it gains slowly compared to other altcoins of its caliber. But, to me, I would take that any day compared to a coin that could grow quickly, but you would only have a small window to exploit. I would rather see little profit than end up gaining nothing, moreover losing if the asset would go lower than the amount you bought it for.