[Shield Tablet Q&A, Help & Troubleshooting] amartolos:
Since you're not familiar to the terminology, I'll give you the "concise" (I sometimes ramble...) summary of my understanding:

1. Rooting is giving yourself full administrative power over every single file and operation on your phone. Use this power responsibly, meaning think twice before executing a command and bear the consequences like an adult (or enjoy the benefits like a giddy goof!)

2. Recovery is a partition on your device's storage. Stock recovery usually only automatically performs the one task of factory reset/wipe of your device's data, but a custom recovery can allow you to flash (install) programs or even a customized version of the whole operating system (a custom ROM).

3. ROM technically stands for "Read-Only-Memory" but these days it refers to the actual operating system that's residing within that read-only-memory. You've heard of the Cyanogen ROM, which really means Cyanogen's customized operating system for your read-only-memory.

4. Kernel is basically a magical piece of software that tells your device's hardware how to function. So, if you use the wrong kernel, your device's hardware won't know how to function properly and you'll run into problems. But using a customized or optimized kernel will allow your hardware to function much more efficiently or unlock abilities that your hardware didn't know it could do (e.g. undervolting to save power, communicating with USB devices via USB on-the-go, etc.)

5. TWRP and ClockworkMod are both examples of very popular recovery partitions. Some people prefer one over the other. I personally like TWRP because it has an easier to use interface for me.

6. Unofficial vs official mods are best discussed using an example like a cyanogen ROM. An unofficial cyanogen mod means that it's not officially made by the Cyanogen team and is therefore not supported so you can't go crying to Cyanogen if you've messed up your device using an unofficial mod. Official mods are the stuff officially released by Cyanogen and will be fully supported by their team.

I hope the above helps with your understanding of some terminology. Below, I describe my opinions on whether rooting / custom ROMs are worth it.

I'm currently using the nVidia stock firmware, so I'm not using a custom ROM. The downside is that I miss out on the great customized features like clearing all recent apps from memory, or holding the Overlay button to switch to my last-used app, etc. The upside is that I get to use the nVidia-specific features, such as stylus-only mode (I use it a lot for annotating PDFs / research papers / drawings etc.) or the Console Mode for when I hook up the tablet to the big TV. I've tried a custom ROM and loved the somewhat increased smoothness and extra features, but I personally wanted the nVidia-specific features more than the custom features.

That said, I have rooted my stock nVidia firmware because I wanted to block ads without downloading or purchasing an additional app. I've used the root privileges to allow me to modify my hosts file to redirect ad URLs to 127.0.0.1, which gives those ads no data therefore effectively blocking them. That's all I use my root privileges for, and some of you might think "that's it?!?!" and to that I say "yyyyyyup".

Long post, but congrats for making it this far and thanks for reading!