Three hundred thousand players is actually a pretty good number these days. In fact, CCP was extremely happy to announce hitting the 300k+ mark today, on EVE's 6th birthday. Most MMO analysts would probably say WAR is one of the top 5 subscription MMOs in Europe/North America.
On the other hand, EA and Mythic can't be too happy about the current population situation since Mark Jacobs has made a couple famous remarks about population numbers in the past. The first is that WAR would be successful if it had north of 500k subscribers. The second is that 250k subscribers doesn't look too good to investors when you've made an initial investment of over $50M and have high maintenance costs. You might also want to factor in that Mythic started a recruit-a-friend program, free trial, and launched in Russia all during the period of the quarter being reported on.
With Aion set for release in fall 2009, WAR may soon face some stiff competition on the PvP/RvR front. A lot may be riding on Mythic's new live expansion, The Land of the Dead set for release this summer.