ME1 has had the single most engaging storyline of any game I have played for the past 20 years, and I have played all the classic RPGs/JRPGs of yore.
Noveria, Virmire and Ilos and the ending were all top-notch stuff.
ME2 was more playable, but the story lacked the epicness of the first, and the final battle was a bit iffy.
People arguing about the RPG elements being stripped out of ME2 seem to have different opinions on what RPG elements are. ME1 had more stat-based RPG elements, with a more complex levelling-up process and standard "billion things in my backpack" type inventory.
ME2 simplified these, but the actual RP parts, whereby the choices you make in the game have noticeable impacts are greater than in ME1. ME1 had you making key choices that rarely showed their impact in the duration of that game, and whereas ME2 has similar options (Geth, etc), it also had for immediate impacts (SPOILER: Zaeed's loyalty mission, the Turian's loyalty mission, various crew-members locking horns and your handling of that affecting the final battle)
I loved both, ME1 for it's compelling storyline, and ME2 for it's characterisation.