Okay, first let me say that in my opinion if you have the chance to buy an Ody2 but are hesitating because you think the Ithaka will be SOOO much better and you don't want to feel you've wasted your money, just go ahead and buy the ody. The differences between the two are for the most part about making it a little more versatile and addressing a few suggestions that a few people have made on the forums. Don't get me wrong, the Ithaka is an evolutionary atty (yes I meant evolutionary). Meaning that everything that all the little things that people have said they would like to see changed have been. At the same time though I can see several changes to even the Ithaka's design that he will make further down the line. And I feel that the Ody2 is a solid piece of work that has no true flaws and I would NOT suggest holding out for the Ithaka IF you get the opportunity to buy one.
So here are the differences in a nutshell. And let me say, unless you have an Ody2 most of these diffs won't mean a thing to you.
-First the notch at the top sides of the ceramic used for the wick/wire are deeper to accommodate thicker wick or the use of multi-wick.
-The negative wire now connects at the base post much like the positive lead does.
-It comes with a clear window instead of having to either buy a window and extension or buy a custom window from Kir (what I do since you can't ever find an actual GG extension and because Kir has windows of 4 different sizes)
-The method of connecting the ceramic and atty to the base uses a wide ring rather than a thin nut. This has several purposes but mostly just so you can set it to always have liquid flow rather than unscrewing the neck. To me the is NOT an improvement since once you have set you can't change it without taking it apart again. And the whole point of the Ithaka, Ody, iAtty, Ody2, etc is the control of air, liquid, etc and by making it so the liquid is always on is a step back. If you want it on a little just unscrew the neck a little, if you want it open a lot unscrew it a lot. I can't think of any (good) reason why you would want it to always be open but I can think of several reasons why you would want to be able to completely cut off the liquid flow including the desire to put it in your pocket or purse without it leaking.
-You can adjust the length of the center post easier. This allows for better connections using various fittings such as 510, ego, 801, etc. Again, this is not a new feature just an improvement over the current one. I can adjust the length on the Ody2 but it's easier on the Ithaka.
-You can add a piece to the base of the Ithaka to use on a 510 rather than having to drain, and change the base. For me, when I think I will need to use my Ody2 on both the GGTS and a 510/Ego I just use the 510 base it came with rather than the GG base. All the features are the same between the two it's just a different configuration is all. Again, this is a great new enhancement but it's not really something that 'had' to be done.
-The tank cap can be used like the Ody2 for easy fill or the top cap, which is used to make the seal around the neck, can be removed so it can be topped off with a little more liquid much like the Penelope cap is designed. Again, I do the same thing with the Ody 2 it just requires the additional removal of the o-ring which is fitted into the cap of the Ithaka so it stays in the cap when it's removed. Also interesting to note that when filling this way on either the Ody 2 or the Ithaka it will still require the use of either a bottle with a needle tip or a syringe.
-Has the ability to add another adapter that allows air flow control just like the GGTS for when using it in another configuration such as 510/ego. It's like taking that piece off the GGTS and putting it on the bottom of the Ithaka. Again, this is only useful when using on something other than a GGTS. And it's another piece to buy which as we all know is almost impossible to do.
-Allows you to put a 510 drip tip into the neck rather than just using the neck. I do like this feature. So much so in fact that shortly after purchasing my Ody2 I bored out the neck. Which by the way is exactly what he did on the Ithaka!
I know I missed a few features but this is the bulk of them in a nutshell. And please remember, I have included my opinions as an avid GG user just for your information only. They are my opinions and I don't expect everyone will agree. I believe the Ithaka to be the next evolution in what is (again IMO) the best line of rebuildable attys anywhere. They are expensive and EXTREMELY hard to find but that is just because they are SO incredibly good and he cuts NO corners on a single one. He listens to the people who use these every single day and makes the next model with their ideas in the design. I would say to anyone who is interested in getting one to step in line as soon as you can and place your order. But, again I would also say to those who can only have one or the other and have the opportunity to buy an Ody2, snatch it up now! You won't regret it, not even when the Ithaka is out.