Sandow's dumbbells 6 kg training first impressions

As the post's title says my first impressions are as follows: biceps exercises are hard to do; alternate form of the 4th exercise is difficult to do and I can no longer keep my arms in horizontal position;  the 5th exercise is much harder to do now; of course I can hold my arms at the shoulders level for a shorter time now during the rotational exercises; I didn't notice a very big difference in other exercises.