Mass Effect is huge (maybe a little too huge) and very fun.
First off, the shooting aspect is very fun. You basically sprint into cover and gun down baddies with whatever gun or magic you choose. Its simple, but that's what makes it fun.
A quite annoying problem is that this game gives you very few directions. I spend long amounts of time trying to find my way to my destination.
BUT, when I do find my way, I have huge amounts of fun gunning down the Geth while listening to Avenged Sevenfold, so its usually worth the trouble (Avenged Sevenfold is great shootout music XD)
I would recommend this game to pretty much anyone with patience who enjoys shooters mixed with rpgs.
Yes! Its part rpg as well!
You spend quite a bit of time talking political matters and stuff (I usually skip through it all and let my character say whatever he wants).
All in all, a huge game, which would've been a higher grade, had it not made me run around looking so much.