Absolutely they are. Most of my friends and family are Pixel users and we all communicate using RCS. If Apple would just support the modern replacement for SMS (which includes end to end encryption), iPhone users would be much safer and would have a better experience.
It apparently just doesn't work with dual-SIM phones, requires a phone number and an active plan with a supported operator (at least iMessage lets me use an email address!), the multi-device story is non-existent, to just name a few.