It took me about a week to get ME2 finished, and wanted to get through the whole thing before I wrote up a review.
Finishing up sequel to an original I love is very satisfying. Seeing a great game being vastly improved upon is even better.
Visually, ME2 is amazing. I never thought it could look any better than the original and Bioware proved me wrong (thank goodness the giant Chiclet teeth have been done away with). Facial expressions, tracer fire, everything just makes the game quite beautiful.
Despite the changes in menus and combat, and the addition to planet scanning and equipment research, the learning curve doesn't increase drastically. With the addition of diving into cover, it makes combat a bit more strategic in where combat allies are placed. Hacking is also completely redone, and allows for even a soldier to get into the hardest of places without the need to carry a tech along everywhere.
Storywise, ME2 lags a bit behind the first game in this department. ME1 gave you the focus of a bad guy the entire time, having to prove yourself to the Council that what you were doing is right, and adding an amount of desperation to bringing down an indoctrinated rogue Spectre. ME2 tells you who the enemies are from the beginning and lets you follow your own thinly-veiled path as to how to get things done. Where it lacks in story, however, ME2 makes up for in choices.
Romance opportunities aside, there are also loyalty quests for each character on your team. They don't ever need to be accomplished, but the player will see the consequences for himself if he doesn't. There are also choices as to what upgrades to add to your ship, which also alters what cutscenes the player will get in his/her final battle. Importing an ME1 save or starting from scratch in ME2 will also produce different results and story plots to occur. I applaud Bioware for trying to keep things consistent between games with choices I made in the first game and how they affect things in the sequel.
A great game sequel with very high replay value and elimination of driving around that stupid Mako.