Oh indeed it gets better with BN2, so much better I'd say.
To put it simply, BN1 and BN4 are the low points (even more so BN4, it's horribly designed, meanwhile BN1 is just barebones)
BN3 and BN5 are very good and solid games, but have something that holds them back (BN3 has too much backtracking, like... Only one boss scenario on BN2 is about backtracking the entire net and it's at the end, but on BN3 there's at least 3 of these and each one takes forever, BN5 on the other hand has mandatory tactic RPG missions at some parts, you either love them or hate them to bits)
Now, the masterpieces which are BN2 and BN6. Both are really, really good and have great pacing. Mechanically, BN2 is simpler but it still got plenty of stuff everywhere, BN6 as the last one has a lot more stuff to consider in each fight, even to a point where the things you get can be so powerful, you'll be unstoppable as long as you manage everything correctly, so there's a lot more strategies. Both have the best plots in my opinion too, and the best balance of mechanics and strategy. Give these a chance at least :]
Also, you'll enjoy the games more if you try to go for unique strategies with what you have at hand. Learn how to use the folder and letter system to make each battle more fun or search for guides to get ideas since most of the meat is hidden in obscure Net areas and small details in the overworld.
https://www.therockmanexezone.com/ has a lot of information of each game so check it out if you want.
