I'm 59 and I've been a fan of Motocross and Supercross since I was a kid so I'm a bit biased. I own every MX and SX game Milestone has put out and they have improved the games with each new installment.
Supercross 2 is a very good game in my opinion. You will get out of it what you put into it. If you like running short races I wouldn't recommend this game , if you get back in the pack in a short race you just won't have time to get back up front. Also short races just don't allow the games realism to show through. In the longer races the tracks will rut up (not as much as I'd like but a bit) and you will make mistakes. Anyone can run 5 to 7 laps cleanly but run 12 to 18 or so and you're going to miss the mark every now and then which adds to the realism of the game. I recommend running at least the medium race length , that's a 10 minute main event + 1 lap. Still goes by pretty quick but it gives you time to fight back if you crash. I like running the realistic length 15 minutes +1 lap for 250's and 20 minutes + 1 lap for 450's. Also do the qualifying it gives you plenty of time to get a feel for the track.
A few things to keep in mind. I consider myself a veteran player of these types of games and for the first week or so I was a bit frustrated with the game. This is the first SX game I've played in which you actually have to slow down at times to be fast , in other words you can't just blast around the track at full speed. Corner speed matters and there are some jumps you will need to let off a bit or you're going to over jump and get way out of shape if not completely off the track.
Also at first your bike is not going to feel real great until you earn enough credits to upgrade it , then the handling gets much better and you will be more competitive.
Learn the tracks - this is crucial as it is in most racing games. The better you know the track the better you will do.
I ran my 250 east and west seasons on medium difficulty just to learn the tracks and get some credits saved up. 450's I bumped it up to hard but now its time to take it up to realistic.
If you're a fan of the sport I think you will enjoy the game. My only real complaints are the tracks do not rut up enough and the off track timer needs to be toned down. They some times just don't give you time to get back on track before they just re spawn you , and I wish we had the current 2019 season instead of last years, but that seems to be the norm with these games. It's just weird seeing the riders on the manufacturers bikes that they are not currently riding in real life.