P990i has a bigger physical screen size than the n73...plus it is a QVGA touchscreen....and guess what, the icing of the cake is the wifi.... which is absent in n73...only drawback with the p990 is tht it has a 2 mp cam as compared to the n73's 3.2mp...also, the p990 tends to get slow..but i've heard tht the problem has been solved to a large extent in the new firmware...so it shud be okay...anyways n73, itself is a bit slow.. so it shud not be an issue..
Also the size of the p990 is something u'll have to get used to..else, at its current price..its a damn good buy...