Total newbie here but I'm in the middle of Lord of Chaos so I'm tempted...
I really want you to join, but I would advise you at least complete 1 normal game first.
Btw, that book has an awesome ending.
I don't know why I said Lord of Chaos. I'm actually in the middle of Fires of Heaven. This book is apparently when everyone slows way down, although I haven't had a problem with it yet.
Having quickly looked at the plot summaries of the series, I don't think it slows down until Lord of Chaos, then it picks up again in Winter's Heart. That's not to say that the books in between are bad, or lack plot.
Very minor spoilery hints at what might happen in later books:
There's still lots of things happening they just don't seem to progress as rapidly as the previous ones. At that point I'd say the series seems to actually start wrapping up some of the many plotlines introduced in earlier books. I'd say that around Lord of Chaos it is more accurate to say that the books start to suffer from character bloat. Too many perspective characters that are all doing different things, so the story must jump from person to person who are in totally different settings that need to be explained. Around Winter's Heart they stop introducing new people and start tying up loose ends (some people die, some people just end up in the same room more often, some people's perspective's become less crucial to the story and are thus not told as often). There's a little bit of back and forth in the series where the occasional new character line pops up after that, but it seems more managed. Around Lord of Chaos it starts being problematic, continues to until Winter's Heart where it seems to get under control again. All that said if you like a character they are written consistently throughout so their story lines will continue to interest you even if you occasionally feel like maybe there's a bit much going on.