I guess I don't get why people like Raiden though at all. In my opinion bullet hell + slow ship mix as well as toothpaste and orange juice.
Even as a Raiden lover, I agree that the "bullet hell" sucks and takes the fun out of the game real fast.
Again, this is why, IMO, using the laser and not the Vulcan gun is absolutely critical. Nowhere is "the best defense is a good offense" more true than Raiden. So get the laser. Next, pay attention to where the massive, bullet-spewing tanks and battleships enter the screen on each level. When they show up, you typically have a couple seconds before they cut loose and fill the screen with bullets. Be waiting for them! Position your ship halfway up the screen so you can pump shots into them faster and fire at nothing until they show up. The laser will cut just about anything to ribbons before they can open fire. On the rare occasions you do end up with a certain-death swarm of bullets heading your way, drop a bomb and shoot from behind the protective blast radius.
Not using the Vulcan gun means there's a lot more riff-raff flying around and I recommend pairing the laser with the homing missiles to help clean up the small fries.
To summarize, here are the Strategies for Raiden Enjoyment:
1) Buy the SCD for the music.
2) Use the laser and homing missiles.
3) Hose the big brutes before they get a shot off.
4) Don't die.