Pros and Cons of flashing your Symbian device into a custom firmware

Ever seen someone's symbian device same as yours with a different and more powerful user-interface than yours. Huh? Am I blabbing?
No! flashing your symbian phone with a custom firmware (CFW) is like installing a new software to your device packed with new and amazing features.

This is different from updating your phone's firmware. It is in some ways but in this case, you are not installing the official firmware from your phone's brand but that of third parties (Mobile Phone Hackers and Co).
Honestly, I'd say CFW is more great to use and fun to wok with; Other than official firmwares.
Getiing it straight...

PROS:

You get a whole new symbian phone experience depending on the brand you use
Your phone comes with a dynamic user interface integrated by the modder/CFW creator
New tools and utilities for office work and mobile playground i.e the CFW can come with apps like Free PDF reader, 3D photo-browser, zip manager and likes
Certificate Error Killed: Most modders include hacking tools to fix and conquer certificate error displayed during installation of some unsigned apps. Not all apps on the internet are signed and without hacking or installing a CFW, you can't ever install these apps on your symbian device.
Improved RAM allowance: On startup, you get to have bigger RAM size available for you to run apps and programs
Updated Apps and Programs: Default apps and programs natively installed into your phone's default firmware will be updated e.g Your Nokia Browser (On Nokia Phones) will be a latest one and believe me, There's tons of apps that's gonna recieve updates via the CFW
A better UI: The modded versions of firmwares present a better User Interface as compared to native/default firmwares. Like editable home screen icons amongst others. Also, your phone can run user interface like that of bigger Symbian Devices you are hoping to have.

New Symbols: Your CFW may come with some blackberry symbols or powerful and hardly discovered symbols like that of Facebook, Pepsi, Nickelodeon.... (I have them currently on my Symbian device)

Wish to have those features on your phone? Don't get too carried away; Everything that has an advantage has a...... :-) CONS:

Ab slight error while Flashing could crash your phone
Flashing with a lower version of firmware to the native one could brick your phone (DOWNGRADING)
Most Apps installed by default will be no where to be found; You have to install them manually. An instance was when I flashed my Symbian device into a CFW and I had to install an app (YouTube Downloader) which requires QT to run; I had it on my previous and native firmware but after flashing, all were gone so I went searching for QT app all over the internet gulping about 200mb of data on my phone without finding the one that works effectively on my phone. It made me regret ever flashing my phone.
PS: I'm still happy I did
Your phone isn't the same like you bought it new again because you have customised it and no assurance for a Warranty anymore.

Convinced? Tutorials on flashing your symbian device can be found here. Got more questions to ask regarding this? The comment box is free to use.