Jak 2 is tough as nails your first time through but after that it's fairly easy. It's my personal favorite in the series because I liked the enviroments and what the guns added to the gameplay. Jak 3 would probably be my favorite if it wasn't for all the vehicle missions, but all in all you should play through the entire trilogy and then judge the games. You never know, Jak 2 may just grow on you.
PSN: extremeM
PlayStation Vita Japanese Software Sales (Media Create Physical/ Famitsu Digital)