I guess I'll step up to bat and give this a swing...

Free Pros:

[indent]Free is a good place to go if you're looking to scratch that Rping itch but don't really have the dedication to invest heavily into a RP. Not to say that free can't churn out some fairly high quality stuff; Free has pretty much no limits, so you can be as verbose or latonic as you want. Sometimes you might even find what I call "Walk-On" Rp's; pretty much you establish yourself as someone who will be joining with a character in mind and just go wherever the story is going off right than. Additionally, I like using Free as a "Field Test" for some of my RP ideas that I want to GM. Free doesn't require much aside from listening to the GM while they're there. And if it flops, than you can just take notes of what worked and what didn't, give it a week, and start over.[/indent]

Free Cons:

[indent]Let's be honest: Everyone thinks that Free is the noob area. You'd get all types of Mary Sues, Online twats, trolls, and just about every other negative player types. Granted, you'd find them at higher levels too, but in Free it's more likely that they'll stick around simply because of Free's fairly low standards. Worse still is those who, again being honest, are not good writers. In fact some of them will be very bad writers (Those Mary Sues aren't well thought out). But in Free, if the GM doesn't keep a standard, they allow those players to keep making those crap characters and don't really evolve. Some say practice makes perfect: I disagree. [b]Perfect[/b] practice makes perfect. Players who don't hit that level of "Perfection" by the standards of say, Casual, will always be writing at Free's worse. This largely is dependent on the GM's ability to weed out or help their players, but in free sometimes they just don't care.[/indent]

Casual Pros:

[indent]Like what most people have mentioned, Casual is that golden zone between the independence of Free with the skill of Advance. Often you will find that many of the Casual players could very well qualify for Advance. Casual's requirements usually just warrant that you are able to maintain attendance (And tell us if you are going to be missing) and largely doing as the GM says. While they don't accept bad writing in terms of spelling and grammar, they're usually willing to help you out on it and let you try again. Casual RP's tend to have more story behind them too; some of them are heavy in lore while others provide just enough to allow you to head into the world knowing what you can do, but with the ability to add onto it yourself. [/indent]

Casual Cons:

[indent]The term "High Casual" has it's merits and flaws. While it implies that the RP is almost advance in writing quality, it also inadvertently says "GTFO Free". High Casual is a way of saying "We want to write in depth about the story but without the constant paragraph churn out of Advance, but without the low-level scrubs of Free". Additionally, just as often as you'd find casual GM's and players are are friendly, you'd find as many Casual GM's and players who are rather bullheaded. They'd harp constantly about you actions or characters under the impression that they're trying to help you, when you in turn may just get the impression that they want you to play as what best fits their characters instead of what you'd want. And the thing is, they're neither right or wrong; sometimes you are writing such a horrible character that others are going to give you a hostile whipping, while other times they're just egomaniacs who insist they know what they're doing. Some may even admit this (I do).[/indent]

Advance Pros:

[indent]Advance can be one of the greatest experiences in your life. Everyone there has an understanding of what they can do and what their place is but also know each other well enough to creating works of art in the form of text. You come to Advance when you want to feel like you're part of a bigger world, even if you yourself is only observing it. If you have a passion for writing and the willingness to keep at it, Advance may soon be your home.[/indent]

Advance Cons:

[indent]You see the issues Casual has? Same here, but instead of it merely being a possibility, it's the standard. You don't come into Advance expecting that anything will be fine. you have to write a character that is not only deep and likeable, but also synthesis well with others. They could either be the best of friends or the worse of enemies, but either way, it's not something that can merely be "up to chance". There's a certain controlled chaos when it comes to Advance. On one hand a lot is happening and it's nearly impossible to keep up with it. On the other hand not many are willing to help you figure it out because you're suppose to already know this. You don't go into advance with a casual mindset; you go into Advance under the impression that you can be there when it needs you. Not all the time, but the windows where you're needed are small and often random. As others would say, Advance is slow pace, but don't think that it can't catch you by surprise if you haven't been watching it like a hawk.[/indent]

Those are just some of the general impressions I get from all the forums. I won't say that they're accurate or true, but that's just what I get from them. Maybe you might understand, maybe I'm just a weirdo. Hopefully it helps somehow.