For those talking about ratings:
Mass Effect
Aggregate scores
Aggregator Score GameRankings
(X360) 91.24%
(PC) 89.70%
Metacritic (X360) 91/100
(PC) 89/100
(PS3) 85/100 Review scores
Publication Score
1UP.com A
Computer and Video Games 9.0/10
Edge 7/10
Electronic Gaming Monthly 9.17/10
Eurogamer 8/10
Game Informer 9.75/10
GamePro (4.75/5)
GamesRadar 9/10
GameSpot (PC) 9.0/10
(X360) 8.5/10
GameSpy 




GameTrailers 9.6/10
IGN 9.4/10
Official Xbox Magazine 10/10
X-Play 




Mass Effect was met with overwhelmingly positive reviews from general publications. Combat and visuals were receiving generally positive responses but much acclaim was given to interactive storytelling, great characters, dialogue, choices and atmospheric scores. Several reviewers deemed Mass Effect as the "Best story ever told in gaming history". PLUS: Many Game of the year/RPG of the year.
Mass Effect 2:
Review scores
Publication Score
1UP.com A-
Edge 9/10
Eurogamer 10/10
Famitsu 35/40
GameCritics 7.5/10
Game Informer (PC,XBOX ans PS3) 9.75/10 9.5/10 9.75/10
GamePro 








Game Revolution A- A- A-
GameSpot 9/10 8.5/10 9/10
GameSpy 








GameTrailers 9.7/10
IGN 9.6/10 9.5/10 9.6/10
RPGamer 5.0/5 4.5/5
Aggregate scores:
GameRankings 94.52% 93.24% 95.69%
Metacritic 94/100 94/100 96/100
Critics praised multiple aspects of the game, including its interactive storytelling, characterization, and combat. In contrast, some reviewers expressed concerns about the game's simplified gameplay compared to the previous game in the series. The game received numerous year-end awards, including Game of the Year at the 14th Annual Interactive Achievement Awards, and Best Game at the 2011 British Academy of Film and Television Arts Awards.
Mass Effect 3:
Aggregate scores
Aggregator Score
GameRankings (X360) 92.17%
(PS3) 91.65%
(WIIU) 87.76%
(PC) 87.75%
Metacritic (X360) 93/100
(PS3) 93/100
(PC) 89/100
(WIIU) 87/100
Review scores
Publication Score
1UP.com A
Edge 8/10
Eurogamer 10/10
G4 5/5
Game Informer 10/10
GameSpot 9.0/10
GameTrailers 9.5/10
IGN 9.5/10
Official Xbox Magazine UK 10/10
PC Gamer US 93/100
Awards Publication Award
Game Informer Game of the Year
PC Gamer (US) Game of the Year
MSNBC Game of the Year
NY Daily News Game of the Year
Financial Post Game of the Year
Sentinel & Enterprise Game of the Year
IGN Best RPG
Game Trailers Best RPG
Spike VGAs Best RPG
Official Xbox Magazine Best RPG
Game Informer Best DLC - Citadel
Gameplay in Mass Effect 3 is influenced by decisions made in Mass Effect and Mass Effect 2, for players who have completed those games. It was nominated for five awards at the 2012 Spike Video Game Awards and it won Best RPG of 2012.
Like its predecessors, Mass Effect 3 was released to commercial success and critical acclaim. However, the game's endings were criticized by many players, prompting the release of a free extended cut DLC (downloadable content) which elaborated on the consequences of the ending chosen and the choices made by the player throughout the series, as well as filling in several perceived plot holes.
EDIT: Fixed formating