Given five years of GRUB2 development going into GRUB 2.02, this is going to be a big release and the RC1 release has many new features.
Some of the new features for GRUB 2.02 include morse code output support using the system speaker, new graphics menu options, improved FreeDOS direct loading support, a TrueCrypt ISO loader was added, improved EFI support, enhanced network support, GRUB Legacy configuration file parsing on EFI, ARM U-Boot and EFI ports, ARM64 EFI support, a new grub-macbless utility, support for USB debug dongles, a few performance improvements, native MingW support, several GRUB utilities were rewritten in C, GRUB can now be installed on EFI under Windows, build system improvements, and a variety of other work.
When it comes to GRUB2 handling Coreboot there is now CBFS support, support for launching a payload from flash or disk storage, Coreboot frame-buffer support, and various other improvements.
File-system/disk changes include ZFS features support, ZFS LZ4 support, ZFS V5 support, LVM RAID1 support, GPT PReP support, proper handling for LVM partitions, compressed HFS+ support, experimental 64-bit EXT2 support, and various other file-system handling updates.
Hopefully the official GRUB 2.02 release won't be too far out now that there's been the first release candidate, but then again GRUB 2.00 was long overdue and it's been three years already since the GRUB 2.02 betas began. Those wanting GRUB 2.02 development code now can clone from Git.