It's had very little effect on our day-to-day - yeah, it's cost us real cash money in lawyers, and additional training for GDPR, but most of what is going to be legislation we were already doing. As an individual I welcome this legislation - it should really help to stop the shoddy practises that clearly go on (based on the amount outrage I've seen on this issue). GDPR seems, to me, to be proportionate and reasonable.
I don't see this helping US SaaS companies, because once GDPR is in-place then I'd consider EU SaaS providers to be more attractive. It's a real selling point that your data isn't leaking or being mismanaged.
If anything I see this as a potential boon for the SaaS companies doing their job properly, because the companies that have in-house systems (or have their own bespoke solutions) are going to have to prove those systems themselves - and have all the answers to The Letter. Whereas a good SaaS company can take those problems off their hands.