I like Hashflare in general but they have two problems at the moment: Their prices and the current Exchange Rate

They increased prices before christmas. It was $1,50 per 10 GH/s and is now $2,20 for BTC mining.
While this was still ok when the BTC was high it is more difficult now with the lower BTC. At the moment expect ROI within 4-5 months (was 2-3 before).
I addition their maintance fee is a fixed $-Amount but will be deducted in BTC (so the lower the BTC the higher the fee)

Same ist for ETH mining (also this is maintenance free). ROI was around 5 months, down to 3-4 months before the ETH followed the BTC down from his max. and is now closer to 6 months.

So if you expect that Cryptos will go up significantly again and you have no problem to hodl your mined coins some time than it might be still a good thing.
If you expect the Cryptos stay at the current level for a very long time (or even go down further) it might be not a worthwhile investment.

For me I currently re-invest mined BTC into more ETH mining power as I expect the ETH to have more potential to rise again. But this is just my opinion!

One more remark: The min. withdraw for BTC is quite high at over $500 (but should decrease again sometimes later). Ether min withdraw is around $95.