I don't know what the numbers are concerning how many players there are in DDO; however, I'm willing to bet that not many players know this forum exists. However, with a little word of mouth, that could change.
DDO is still ticking along.
Like Katheryne, I don't know the numbers.
However, I recently did the n-day trial (I forget how long it was), and it seemed pretty active.
Personally, it didn't grab me well enough to get me spending money on it.
But, that in no way means that anyone else won't enjoy it.
If you don't, or haven't already, I would recommend at least trying the trial for it.