ETH and all the altcoins are severely depressed now. It is really a tough spot for such a decision. On one hand, they are very cheap compared to Bitcoin and they are worth buying, but I wouldn't expect any major surge in the short term until the end of the year.
ETH is stable and good for long term. Yes, it is good to buy now while its price is cheaper. You should grab the opportunity now to load up before the market bull run.