HBO's first attempt (before Game of Thrones) in epic storytelling delivers in spades! Rome, during its short two-season arc, felt at times rushed, but never lost its quality.
Rome is the story of Caesar, Mark Antony, Augustus, Cleopatra, and two common soldiers. All of these characters are developed exceptionally well! Their character arcs evolve from villains to heroes, and then back to villains again while you still care for each of these characters (unlike the characters on Boardwalk Empire for example). For the modern audience, Rome can be best described as the amalgamation of House of Cards and Game of Thrones - although Rome precedes both! Rome also serves well as the spiritual successor to Spartacus (made in almost a decade later, and reviewed here).
I had a small problem with the story, particularly in season one. Two of the integral characters, Atia and Servilia, take actions for petty reasons (such as jealousy or rivalry for attention), and manage to have a major impact on the Roman Republic. In other words, the consequences were disproportionate to the intention behind those actions. Of course, it is hard to write strong female characters. But the show found a much better balance in season two.
As for the looks of the show, the beautiful sets are designed with utmost accuracy and respect to the source material. These sets are also partly to blame for the short life of Rome, as the high production costs were the reason for its untimely cancellation. I have read online (on IMDb and Wikipedia) that Bruno Heller (the showrunner) had detailed the plot of five seasons; but midway through season two, he was told that it would be the last season. Hence, he crammed the plots for seasons three and four into the latter half of season two. Some say that this fast-paced storytelling negatively affected the quality of season two. I, however, preferred season two to the slower season one.
Overall, Rome is a beautiful show, perfectly cast (and acted), and surprisingly accurate to the history. It was a 9.5/10 for me.