[Tuor in Gondolin]

I thought the cloak sequence was allright by PJ,
including the bad guys not seeing the hobbits when near them.
However, as to the Rohirrim not being enemies, in the
book, while not enemies, Eomer seems to say they are
not yet, at present, allies.

I serve only the Lord of the Mark, Theoden King son of Thengel. We do not serve the Power of the Black Land far away, but neither are we at open war with him; and if you are fleeing from him, then you had best leave this land.

I thought PJ's making the phyiscal interaction on deciding how to procede:

All of that math must have gone to Sam’s head too, as he gets a little too close to the edge and falls over. Nice, Sam, I guess that your plan was to run down the hill while a thousand or two bad guys are tramping around out front. Another instance of a character going out of character for a thrill.

was much poorer then the book discussion. He presumably did it to
get action and use of the cloaks but it is, as noted above,
rather illogical.

And one of the most incomprehensible decisions of the movie has its
seeds here, showing Pippin and Merry growing, and then later (especially
at the Grey Havens, showing them shrunk down again. If you go to the
effort and time of having them grow why then ignore this later. PJ could
even have had a better Gimli humor moment by using his book
comments and measuring of the hobbits at Isengard.

Again, here PJ and friends put on an aggravating combination of
occasional story faithfulness and great effort in scenery, etc. with
counterproductive "changes", some comprehensible and others not.