Concierge.com's insider take:

Though the Merrion opened in 1997, it feels like the oldest hotel in town—not least due to the Georgian wing it has retained. In a city of spotty service, the staff here does a good impression of having had decades of practice, and the look of the place is weathering beautifully—with one caveat. The pricier rooms and suites in the main house are so much more charming than those in the contemporary Garden Wing. The former have high ceilings with picture rails and moldings, gracious proportions, cornflower-blue walls, taupe carpets, and (sometimes) fireplaces. The Garden Wing rooms reverse the color scheme, with dark blue carpets and beige walls; though perfectly comfortable and offering pretty views of the 18th-century landscaped gardens, they're boxy and bland. Still, all 123 rooms have individually controlled AC, satellite, and cable TV loaded with PlayStation games, plus Carrera marble bathrooms with separate power showers (none of which you can take for granted in Dublin), and, of course, the great location off Merrion Square. The Tethra Spa, with its Roman-style colonnaded pool, is tops, though rust stains and a steam room with a bockety old door signal an area now in need of an upgrade. Dining options include Patrick Guilbaud's two-Michelin-starred restaurant (the best in town), and kids are well catered for, from the room-service Pooh Bear and Barbie crockery to minirobes for the pool.