Hm. I like it, but it's not AAA yet.
-Can you add a dynamic light? a flash that lightsa the surrounding area for around 1 second?
-The smoke could be a little darker in places
-The explosion itself doesn't look "thick" enough yet. It looks like the smoke is always behind the actual explosion (if your explosion is anything like mine, this would be because of the BRIGHT flag. Maybe you can deactivate it on some of the particles at random?)
-The explosion itself has a lot of structure (see first screen) which is great. I don't like the round sparks though (the streaked ones are great), for some reason I don't think they look very good, and I've never seen something like that in any explosions in movies etc, as far as I remember.
-How much would you mind sharing your smoke bmap? I've been trying to work on my smoke, and it's just not perfect -.-... maybe having a look at your particle would help a little...

[edit] I noticed also that a shaking camera (when too close to the explosion) and bits of the exploding object that fly off help a whole lot to make the explosion rewarding to the player. It feels... stronger? that way.