it's simply another layer of NAT and won't affect you unless you are hosting a server (and then you'll need a public IP).
Very up-to-date stuff generally will work OK.
Older stuff, including VoIP/video conferencing, online gaming, remote access software (e.g. VNC, logmein), smart devices (e.g. DVRs), peer-to-peer applications, instant messangers, etc. can have big problems with double NAT, depending on design. The design of the ISP's NAT also strongly affects how effectively this type of application can work. Not all ISPs use "application friendly" NAT routers.
If you have something which doesn't work, then the solution is easy, pay for a public IP. If you find things work adequately, then keep things as they are.