Almost perfect, not bland
The first Halo was almost the perfect first-person-shooter. It had canny AI, perfectly balanced weaponry, and beautifully crafted levels. Its about quality, not novelty. The love and attention to detail that went into the game shone through from almost every aspect of it. It wasn't perfect, but it was a classic of a game. Its this quality that built the Halo brand, its release timing was just a happy coincidence for Microsoft and the XBox. Halo 2 was nowhere near the quality of the first, but initial reviews of Halo 3 seem to suggest they are back on form.