I was very skeptical at first given his low balance and reasonable average agility for a striker. I couldn't decide which chem style to use as I didn't know how it would really affect him ingame. Eventually opted for a Sniper (correct decision trust me) to boost his agility to 98 and give a respectable boost to his balance and composure. This worked wonders - he feels unbelievably agile ingame and his balance isnt an issue at all. Whilst sniper doesnt boost his shot power, his 89 shot power truly feels like 99 when playing with him. He is one of those cards that plays above and beyond his ingame and face card stats, too a point where i wont be removing him from my team unless i can get his 94 / 96. I thought the balance would be a big issue but he has the unique ability to 'phase' through challenges that some of the elite level players have... even if you're not the best dribbler or cock up a run he tends to stumble through the defenders most of the time.
Ronaldo is currently averaging 2.1 goals p/g for me in Division 3 (I'm not the best player this year). If you're skeptical about trying him... DONT BE.
Passes sometimes go awry
77 stamina (not an issue if you put him on conservative interceptions, stay forward)