Happy to answer.
The stock JB keyboard seems to miss auto corrections sometimes. For example, I should never see "tge" or "ti" (just some examples) in any of my messages or emails unless I've actively selected them from the suggestion bar, but they appear. The keyboard should automatically correct them to "the" and "to" and 8 times out of 10 they do but sometimes they don't; it's as if the keyboard missed these autocorrections. For someone who types of emails/messages on my phone, 2/10 missed autocorrections is way too many. I never ever saw this with ICS.
Also, backspacing has taken a giant leap backwards. There's an odd glitch where if you write more than one sentence, then hold down backspace, it'll stop at the punctuation (period, question mark, whichever) of the first sentence. Then you'll have to tap backspace again to finish deleting the rest. In general, backspacing has slowed down tremendously, whereas on ICS, backspacing was incredibly fast and smooth.
And lastly, this happens more rarely, but sometimes random repeated letters or even words will appear. For example, I might type and it'll come out like this: "Hey where do you want to meet up p" or in the case of the randomly repeated word "Hey where do you want to meet up up". It's incredibly bizarre but it happens only at the end of sentences.
As for shortcuts, I think Google REALLY missed the point of shortcuts. It should automatically switch your shortcut to the desired phrase, as oppose to merely offering it up in the suggestion bar. It creates an extra step that is wholly unnecessary. Plus, there are times when the suggestion bar isn't available, like when entering fields or logins/paswords on certain websites. So if you take my screen name for example, on my iPad, I have the shortcut "otca" automatically change to "onthecouchagain". But on my Galaxy Nexus, if I attempt to login on a website or field that doesn't use the suggestion bar (there are A LOT of times when the suggestion bar doesn't come up, even within the OS), it renders the shortcut in JB absolutely useless. Google should just trust people mean what they want when setting shortcuts. It doesn't and shouldn't be a suggestion bar option. I should be able to type "brb" and get "be right back" automatically without breaking the flow of my typing to pick it off the suggestion bar.
And just in general, I feel the responsiveness of the keyboard has taken a tiny step back. It felt slightly more reliable and faster on ICS.
My settings are: Very Aggressive Auto Correction and Predictive Text Off.
Such as?
Genuinely curious. I'm a new Android user who uses JB. The keyboard works fine for me.
I'm curious also, I'm running an alpha build. My stock & thumb keyboard is fine.
Please let me know if either of you have experienced any of this. I already tried a factory reset, and the problem still persists. I'm on Google Play Galaxy Nexus.