I have to say that the AI artillery kinda bothered me in my SPWW2 3.01 campaing, as well as air strikes, but I also have to say it was always my fault - too long resting on one point, forgetting to move support infantry from shell impact zones etc.
Yes, the numerical advantage can be sometimes a pain, but if you had 15 Abrams and he got 50 MBT's, I doubt they were on a good level. AI once attacked my company of M-60's with a fleet of about 90 Shermans (M4A3) and six M-48's and he nearly got me rolled over my forward platoon (he had more tanks than my M-60's got ammo
)), but Sherman vs. M-60 is something I cannot call fair fight.
LOS oddities - I haven't noticed them. Again - dug in ATG can be a pain to spot if you don't have some scouts riding along with your tanks, even worse are ATGM's (as I've noticed recently in one PBEM
))
Now if you wish for games where AI cheats, go for say Battle Isle 1 and 2 and then you'll see that even SP1 and 2 were only beginners in cheating
)