This is by far the best Holiday Inn I have ever stayed in. Although the decor wasn't exactly my taste, everything was spotlessly clean and well kept. The employees were extremely friendly and helpful, especially the concierge! We had the most amazing tour of the city thanks to him. The service is free and I highly suggest that anyone who stays in this hotel utilize it!
The location of this hotel is also good. Although a little further of a walk from the main shopping and sightseeing areas than some of the other historic district hotels, the walk was an easy one and the hotel was basically right across the street from Marion Square--great for visiting the Farmer's Market there early on a Saturday.
Parking is on-site and the rates are the usual for Charleston. There's a pool as well, but I stayed here in December and it was closed for the off season. The rooms are quite large, especially for a downtown hotel.
The one semi-complaint I have is the "Best 4 Breakfast" rate. DO NOT BOTHER BOOKING THIS PACKAGE!!! It is a total waste of money. Their breakfast, while decent, is nothing amazing, and the prices are so low that unless you order 3 entrees and 2 drinks off the menu you will never come close to spending the $20 per person that is allotted to you with this rate. For instance, if the room would normally cost you $179.99 per night, with this package it costs you $219.99 if you have 2 people in the room. So there is no discount or deal and as I said, it is very difficult to rack up a big enough breakfast bill to get your money's worth--because they don't reimburse you for any monies you do not use.
ETA on 1/24/2011: Please note that this hotel has changed ownership and is now a Courtyard Marriott. Despite some research I can't seem to find any updated information or reviews on the hotel, whether or not they still offer the concierge option etc. However, I can attest to the fact that the location is great and as the rooms were quite comfortable I doubt they have made any negative changes to those.