I just want a really basic answer; should I upgrade from 1.0 to 1.3? Is there anything that isn't fixed in 1.3 that was never a problem in 1.0?

patch to 1.3 because the issues that came with 1.2 had been patched with 1.3 and some other things

Get 1.3. With it the game will work as well off the HDD as it did off disc pre-patch, and theoreticlly better in the long term based on patch notes. Bottom line.

yeah the only reason im thinking of getting it is i can install and give my limited addition xbox a break from hours of daily gaming since launch.
i dont think it caused any major issues (if it makes lil bugs ull never notice or no if it was or wasnt the patch) i dont think there is any resistance issues, as ive only ever had 1.1 and my beast blood has caught at least one deisease, as everyone kept saying i looked sick untill i re talosed(which is probably still bugged, i rp using this shrine, what do i get for it, 0% lol, i might as well start worshiping gate posts, they are more common but still retain the 'benifits' of the originals).

Version 1.3 is good. The added bonus is that if you install it to the HDD, then your Xbox is quieter. I used to play it from disk with version 1.1 in order to avoid the texture problem, but when playing from disk, the disk continually spins, which makes your Xbox a little noisy. But 1.3 has the texture fix (I've not had any problems with textures so far, after several hours of playing), and after installing to the HDD, my Xbox is a lot quieter too because the DVD drive isn't continally spinning during the game.

1.2 works fine for me, 1.3 brings back all the problems i had before 1.2 - ugly graphics when installed, some "flying" graphics here and there, at some places missing graphics so i can take a look into buildings without going in and it again started to crash my 360 randomly when loading or saving.

its ruined my game.... thats all ill say

Ugh... so there's no definitive answer as to whether 1.3 is actually making things better for everyone? Scrap my first question, here's another; when can we expect Bethesda to release (the fully functioning, complete version of) Skyrim? 12/12/12?

I just upgraded from 1.0 to 1.3 finally, and see no difference on my system. I still have terrible graphics, dragon flying patterns are extremely glitchy (backwards, sideways, straight down, etc.), and so on. But that might just be my system (Xbox).