LOADS on the InterContinental board about this. For my money, it is as nice (in terms of finish, looks) as any of the grande dames and a lot cheaper - albeit service is not at the Four Seasons level. Great location for most sights and the Haussman department stores.
Do NOT book a Classic room. These are unbelievably small - 20 sq m. Even the Superior and Deluxe rooms are not much better - I think deluxe is 30 sq m. If you are planning on swinging a cat in your room, take a junior suite or above.
If you are staying over a weekend, you will save money by joining the Ambassador loyalty scheme for $150, as one of the benefits is a voucher for a free weekend night at any IC hotel (no restrictions, no black-outs) with a 2-night min stay.