Both systems, a graphical one like Second Life, and text base role plays, like mucks and irc, have there pros and cons. I don't think I could ever give up one for the other.
I'll start with the text based since I've been at them the longest. With text your limited only by your imagination and skill with words. You can paint fantastic forms, scenes and do some very interesting things, to say the least. The draw backs are, for me, in doing idle things. Things like running, flying, wandering aimlessly, the can get a little dull in text. This is where graphic base RPs are wonderful. You can runn around, wander about, and look at things with out needing to read every thing. I love doing such things in second life. The draw backs are that your limited to what can and is created and the quality of the programing, both over all and individual parts. It also lacks in casual actions and expressions which are done all the time, shrugs, smiles frowns waves, things like that. For more intricate things it's worse. Using second life as an example again, with the poses they have you have to first hope you can find the ones you want, and yes, I can think of several that are not out there, then you have to hope they're good quality and will line up....
Why am I writing this.. Just to get my thoughts out. I know many who have left text base for graphic fully, yet I still have much fun in each. Also I was just being in a rather thoughtful mood...