It is not commandments in the Law that are the problem. They are similar to commandments from the same God in the new testament. It is the things that God gave with those commandments especially the curse - the curse if you didn't keep all of them. In the new testament it is still the same God and the same righteousness contained in similar commands but instead of a curse accompanying then to motivate obedience it is promises. In particular, there is the promise of God that Jesus will give knowledge of truthful testimony, along with His revelation of Himself. There is the promise of God and Himself always, eternally, abiding with the keepers and obeyers of the commands. A promise to those who do so in love for Him and for God. It is not to say there were no promises in the old covenant. What accompanied commands of God in the old testament Law is different. It was (is, for those following it) a curse for not obeying - this is its part of its motivation. In the new covenant the curse is done away and what accompanies the commands is promises to those who obey which include eternal life. So the promises are better and the curse is abolished. The old covenant of Law is not abolished but it is made obsolete by the new covenant but the new covenant does include commands - but with just promise, unlike the old which has promises and curses on those who don't always obey it all.
