For everyday net surfing and downloads the connections are good and reliable, but for data flow they are problematic.
It's not that the internet connections are "bad" per se, but you have to understand the Israeli infrastructure problems.
People forget that 50 years ago (even 30) Israel was mostly deserts or farming collectives. Up until about 15 years ago, there was a six month wait (yes, six months) for a home phone line. The country has grown and advanced so quickly that the infrastructure has not been able to keep up (you should see the traffic jams, think I405 at rush hour in LA). If you want, you can order a pro grade ATM or point to point connection but it will cost at least $200/month and possible as much as $1000/month.