[This is a slight adaptation of a writeup I did on the DMTNT expansion for the 1 P:layer Guild from a solo perspective... I realized some of you may be curious also.]
My initial thought when I heard the Kraken was coming was "that's awesome" followed by a solid dose of curiosity.
The very thematic expansion has now been announced, and the Kraken tries to take down the ship while you work to get the treasure off. Even if you do get it off, he's not going to let you flee, so you will have to kill him before you take off with your spoils.
I wanted to test the new expansion with the final rules and let you know what I think of it now but... life happens. And the Kickstarter for Dead Men Tell No Tales: The Kraken is winding up in an hour or two.
So I will let you know what I think based on some earlier playtests and a read through of the most recent rules as posted on the campaign page.
Deckhand leaders: when you draw a deckhand leader, you have to keep drawing! This makes the deckhand threat harder to manage. A fellow play tester and I both really liked this mechanism. You can also now close a trapdoor to slow the spread which counterbalances it.
Adrenaline tokens: these are one-time use tokens you can draw and hold on to at certain points when battling the kraken for later use. Fun and powerful.
Cannons: You can load up some cannons in preparation for later attacks against the Kraken.
The Kraken: Fatigue builds up fast when fighting through tentacles and attempting to hack them off, but you need to save the ship long enough to recover the treasure.
Even though you need to be in the right location to attack the Kraken (and he potentially moves each turn), you can do some prep work when you end up in the wrong spot or when you just aren't ready.
The challenge is that there is a new kind of threat which ramps up quickly - but if you focus on the Kraken too much, other things will get out of control. You may lay tiles differently to help control where the Kraken ends up but that may also make getting treasure off the ship harder, and increase the risk of other threats.
Minis: I actually bought a kraken mini to play with but I do not have awesome tentacles like the expansion comes with! There is a characters mini pack now, and the expansion comes with the kraken and the tentacles you will need to lay across the ship.
In terms of game balance I think it has been tweaked a bit since last I played so I don't want to make any specific assertions about difficulty. As with the base game though, difficulty can be adjusted.
I'm pretty sure I have never tried playing a single character, but 3 characters for a solo player (probably my preferred option), or 2 each for 2 players, or just 2 for a solo player all work well. Most of my tests were 2-3 character solo games.
The expansion might have a bit too much going on for a more casual or brand new player. There isn't much more upkeep between turns (the Kraken means an extra card draw each turn, essentially) but it does mean more balls to keep in the air.