Any experience flying Niki airlines or any other regional European carrier?

We need to take a short trip from Split, Croatia to Vienna Austria in July. We saw a cheap flight on Niki for $77, but the guys drug there feet and it disappeared. I am very low maintenance and always take minor inconveniences in favor of lower prices.

1) Has anyone flown Niki before?

2) Should I jump on the cheapest flight now in case these Euro regional flights only get more expensive?

3) Is it a good chance these carriers add flights at the previous discounts in the near future?

Any suggestions are appreciated.