While my play time has been somewhat limited this past week, I've been spending a fair amount of time on Timeless Isle since the patch, initially focused on getting my legendary cloak, and then more lately just as a way to pass the time while having some more alts wait in queue for LFR. It's been an interesting experience so far.
It seems to be a great way to get additional gear for alts that you don't play a lot, or for a character where you're looking to change specs (playing a holy paladin and want to switch to ret, playing a resto druid and want to switch to feral, etc.). I was able to accumulate a rather huge amount of gear in the short time that I've been on Timeless Isle that has provided a decent benefit to my alts. And it's definitely something different to do other than running dailies or doing pet battles while waiting in queue, which I appreciate.
For my, while it has had a reasonable impact on my alts, it hasn't necessarily been huge, primariliy because, as a result of the process of trying to get everyone ready for SoO, most of my alts were already pretty well geared. So it's had the most benefit for the one character that I had that wasn't at least geared for LFR.
A lot of people have correctly observed that you seem to get a disproportionate amount of drops for armor class of the character that you're playing on. This has actually been a bit of a problem for me as my warlock main is getting mostly cloth drops, but my other two clothies are already very geared and don't really need many upgrades from Timeless Isle. So I've had to be a bit more strategic about who I was playing Timeless Isle on to maximize the potential benefits.
It's likely going to impact the order that I run characters through SoO as well as I'm going to want to accelerate my plate and leather wearers (as that's where I have the most needs for upgrades), so it might push my mage and priest down the list of the weekly order on LFR runs.
The larger benefit was what was apparently a short term boost to drop rates in ToT during the first couple of days in the patch. As a result, my shaman was able to gain an unbelievable 15 points of ilvl during the course of one clear of ToT. In later runs on my monk, that drop rate has been significantly reduced.
So here are the changes in ilvl since my last post (ranked in descending order by current ilvl):
Warlock 519 -> 520
Priest 500 ->501
Druid - 494 -> 499
Mage 496 -> 498
Hunter 486 -> 498
Shaman 477 -> 496
Monk 464 -> 490
Paladin 475 -> 481
Rogue 469 -> 478
Warrior 457 -> 473
The Shaman and Monk have obviously been getting most of my attention the last two weeks and the warrior has been getting the most help from Timeless Isle.