I am a newer Android user and had never rooted a device before or installed a custom ROM prior to installing ThundeROM in early December.
I must admit, I was really nervous but by going slowly and paying close attention as I followed KSmithInNY's step-by-step directions to root the device and, after successfully rooting the Optimus S, then following KSmithInNY's detailed instructions to install ThundeROM I was successful and thrilled with everything about ThundeROM.
I should also mention that KSmithInNY was incredibly helpful and nice enough to answer the questions that I had throughout the rooting and ThundeROM installation process. I cannot thank KSmithInNY enough for his help.
My newbie advice to anyone who has encountered issues with ThundeROM: precisely follow the installation instructions for each and every step; and if you have a question/concern, reach out to the folks in this forum for assistance BEFORE completing that step of the installation process.
Again, thanks to KSmithInNY for developing ThundeROM and continuing to make it even better.