Mass Effect is the template for modern games in general. It has a great story, lots of characters, good voice acting and cool gameplay. Even now, several years after its release and two sequels, it still holds up better than most games.
The orginal Mass Effect has something that its succesors do not have: style ánd substance. The original has hundreds of customisation options. Skill trees are huge and you can easily invest in skills that are not entirely related to your class. It is a bit like Dark Souls in that you can still adopt to suit the situation. You are not irrevocably commited to a single style. This allows you to change things up and to keep the long quest fresh.
This word: commitment. In Mass Effect 2 you would commit to romancing a partner, playing a class and upgrading some weapons. In the original, you spend way more time exploring, fighting and doing cool stuff in general, while still keeping the interactions with your team interesting enough for you to invest in them. Mass Effect is balanced in its commitments, not overly invested in one or the other. It does a lot of things right, but it certainly isn't the best in any area. However, when taken together, you get a very complete and incredible game.
I admit, it may have some problems, like the Mako's gravity defying motions or the tedious shootouts in bunkers that lead to nothing but more worthless junk. However, if you cannot overlook these issues then I suggest you take step back and consider the point of exploring. Bioware has built entire planets for you to explore, and you complain about the space suit you found that happens to be too pink? You are missing the point. If gratification is what you want, then go play something else. Mass Effect is a genuine experience; something that needs to be played to be enjoyed. It isn't the result that matters, but the process.