I have installed a Celesta 1.5 in my Drawing Cum Dining (Approx. 20 X 14).. and the usage is approx 2-3 hrs a day and I say its really effective..
Had got it installed this summer (2002) and all of summer the DCD was cool enough be comfortable...
Ofcourse for such a large area this tonnage is less, but then even 2.0 is small unless its a Split (which was beyond my range).
The A/C post sales service is not one of the best in the market for almost all brands.. and hence I had rely on a product which would give me maximum independence and durability.. my choice was Carrier... since it has proven it over the years .. and has been customized to suit Indian weather conditions...
Good buy I will say, but be sure to negotiate a good price for your product.. the dealers can do away a big chunk of their margin if put under pressure...