Over here on the latest WIP on every save and reopen of a file, all the dims get reset to the Default style. The number format for every dim style in the file is also reset to Decimal (so if was set to feet and inches, on save and reopen it will be decimal). 
The problem seems to be on saving, as a V6 file saved as V5 will open incorrectly in V5, but a file that was saved out of V5 will open correctly in V6.
Perhaps somewhat related, on the command line when getting a distance fractional inches are reported as 1[[1/8]]" instead of 1 1/8"
EDIT
I’ll continue on with a few other dimension / annotation problems as well.
If I am editing text in the properties window, the edit window will lose focus after one key entry.
I can’t seem to override leader arrow head styles anymore. I can attempt to, and the name of the dim style in the properties window will change to [nameOfDimStyle][randomNumber], but the arrow head will stay the same.
This also happens in V5, but might as well put it here as well, if I try and pull a dimAngle in layout space to lines / objects in model space, the result is unexpected (the dim goes way off in layout space). It seems like it is something like the translation between the model cplane and layout CPlane is not working correctly, so try it on model space objects not to close to w0.
If I have my dim style set to display in feet and inches, angles are now also in feet and inches. So 24 degrees now displays as 2’-0" degrees.
If I double click on a dimension to edit it, often times the edit window show the text as italic, underlined, and with strike through even though my dim style text is just plain Arial.
I can’t easily change the text size in the properties window. If I just enter the desired height, I see no change in the text size, if I enter the desired text size and then hit the increment / decrement spin button I get the change.
(Not really dims / annotation, but it’s late and I’m on a roll), the draw order for hatches seems to be less awesome than it used to be for v5. I feel solid hatches in V5 were almost always ordered behind everything, but in V6 they often seem to often obfuscate other hatches (like a cross hatch laid on top of a solid), arrow heads, dim arrows, and text and I have to explicitly call sendToBack on them.
But even with all that said, right now I’m sticking with 6 to finish this drawing package because the layout speed is SOOOOooooo much faster than 5, so thank you many times over for that 
Thanks,
Sam