Very neat character. I went through the main maps and then sent myself into two Chaos Mode maps, and I found a lot more to say regarding this character from playing Master Difficulty Chaos Mode than the main story. (I sometimes run Chaos Mode to see how a character fares against an army of Badniks)
I'll start with the overall moveset. It's quite fun! Being able to just snipe enemies with lasers is cool, and having a slow-yet-powerful explosive is always fun to mess around with. It blowing up the Arid Canyon minecart doors is always a plus.
But wow, having to frantically shake off enemies in Chaos Mode in Master Difficulty was just a bit more annoying than I feel it should be. And quite a few of my issues regard trying to aim the lasers at things.
First off, aiming just slightly downwards (and I mean slightly) makes it bounce... strangely. For some reason, it stops going forward, and bounces... north? I think? It's quite consistent, no matter which way you face, if the angle it hits the floor is close enough to parallel it will bounce in that one particular direction. If this happens, it also seems to get stuck to the floor, so it starts following the slopes downward and whatnot.
The walls, meanwhile, like sucking up the laser beams. Going up against a wall and aiming even somewhat parallel to the wall tends to suck up the shot. If the wall is even somewhat onscreen, you can be sure your shot's being eaten.
Trying to aim down a cliff is also a bit hit-or-miss. You have to move so far forwards to prevent the shots from bouncing upwards, and combined with the recoil moving you backwards it becomes easier to just jump off before firing... before EVERY shot.
When in maps as platform-focus as the main game it's at worst an annoyance. In Chaos Mode's toughest difficulty? It's a nightmare. I swear the laser's hitboxes are bigger than Whisper herself. I hate it. All these issues combined make aiming and firing the lasers way more difficult than it should be, which oddly enough hinder Whisper's ability to actually snipe things. Mostly from above, which is where you get a good view of anything grounded, and thus would be otherwise the best sniping spots.
The rockets are... also hit-and-miss performance-wise. Often, the double-damage and the AOE is a wonderful combo, but the homing is kinda... weak. If the enemy the rockets target move even just a bit away it will likely miss. In addition, the rockets keep trying to home into things it can't actually swerve towards. That, and trying to aim at distant targets (like Badnik spawners) will often just result in the rockets targeting, say, the nearby Eggman monitors instead. Ow.
This means it's sometimes easier trying to blow up a specific target from close-range. Which... considering how you can hit yourself with your own rockets explosion... is a recipe for disaster.
For some reason (performance?), you're only allowed one laser at a time, but no limits on how many rockets, which sometimes makes rockets quicker regarding quickly dispatching distant targets, despite homing issues.
Being totally honest, I haven't tested how practical the Spike attack is at close range too much. To be somewhat fair to myself, I was trying to play like a sniper, and getting closer into danger seemed like a bad idea. Also I just forgot to consider it every time enemies were in my face. That said, I do remember thinking "damn it stop going over the crabs". Also, when I tested against Crawlas, it went over them too, and then I got hit, so I don't think it's effective against grounded robots in general.
The Cube hammer, meanwhile, is one I HAVE tried to use. Believe it or not, but it wasn't too helpful against enemies as agile as Chaos Mode Badniks, mostly because, for some reason, adding the Chaos Mode mod makes it so you bounce off enemies. Oof. That, and there's a lot of airborne foes, so it can't help too much there.
Also was messing around when somehow I got hurt from the basic Crawlas when I landed on it with the hammer? Both before and after adding Chaos mod? Though it's tough for me to re-produce this. It seems super inconsistent. Even tried using Objectplace to help test, and it's safe to say I have no idea why I very rarely just get hit.
ALSO also I don't think the AOE bit has any upward range limit other than "enemy not in air", which means you can cube enemies way above you on a cliff.
Honestly, I mostly want the laser beams changed the most. Aside from fixing the strange direction change, I feel like I want the same change for them as I want for Metal Sonic's Energy Blast in Battlemod: Make its hitbox smaller for terrain while adding a second larger hitbox that only hits players/badniks/stuff. I feel it should be possible, I've seen people add the Insta-Shield. Do something like that, but for a projectile, and make sure the projectile disappears like normal if the bigger hitbox hits a Badnik/player.