Not a lot looks different between stock and MeanROM; what you're looking for is entirely under the hood. In car terms, this ROM would be called a sleeper. There are a few hints here and there that this is not a Sprint issued ROM, but nothing jumps out and requires you to change to use it.
MeanROM was designed on the 2.17.651.5 post-carrier IQ base radios, meaning if you're not on those radios, don't install this ROM without first updating your radios. Otherwise, it will do weird things such as lock up, handle phone calls oddly, force close, order pizza without your knowledge, etc.
I haven't been able to verify the claims on the battery sipping, which are that it can sit in standby for nearly 50 hours when you've got it in stock mode, because quite honestly I don't have any use for a phone in standby mode. On a stock battery running like I run my phone, I could eke out about 10 hours of life; however, I use my phone for nearly everything, so your mileage will vary.
While Quadrant scores are not a reliable indicator of overall performance, this ROM can score above 4000 when pushed to do it. However, clocking your EVO 3D to 1.5Ghz+ to achieve this defeats the battery-savings ability of any ROM, and brings it that much closer to unstable.
MeanROM comes packaged with one of Ziggy's kernels that supports overclocking, and additionally a stock kernel you can flash should you have any issues with Ziggy's. The ROM itself supports HTC Beats by Dre audio, but it's unclear to me whether you have to additionally flash Chad Goodman's AnthraX kernel to achieve the full effect or if Ziggy's includes enough of the modifications. Considering several items on the list say you need to flash Chad's AnthraX kernel, I'd assume a full Beats experience will require the AnthraX experience.
There are two camera apps included with MeanROM, the basic HTC camera with Panorama unlocked and the Amaze Camera, which I've been quite fond of lately on the more recent InfectedROM builds. You can choose whichever you like; each have their pros and cons.
HTML message mode is enabled in Exchange now, but before you get excited like I did, it's HTML send format, so you still see emails like you normally would on any other ROM. No HTML message previews, just text.
The ROM includes the extra real estate added in the 4×5 Rosie Launcher Mod. It's not listed as a feature of the ROM, but is there in the changelog. The extra space just feels right for the size of the EVO screen.
Something I've not had a chance to play around with is the Fast Charge enhancement. Fast Charge is a kernel enhancement that gives your battery all that it can take. It's disabled by default in this ROM, possibly due to many complaints in kernel threads of excessive heat generated when you're attempting to fast charge a battery. Since it's evidently kernel dependent, your kernel will have to support it also.
There are a few little things located throughout the ROM that I find quite amusing, most notably the startup animation, which indicates your reactor is online, and the CRT-off animation. All of the cool root reasons are in this ROM too – unlocked hotspot, roam only, 7-in-1 power menu, Google Talk with video, slide to clear notifications.
As for the things I dislike about the ROM, that list is pretty short. The flashlight app has advertising, the wake with volume rocker doesn't work for me (although Ponury Gesture Mod will), and the developer removed the Rosie Carousel effect. I think that I might be the the only person on the planet that really enjoyed spinning it, though.
After playing with this a while, it's not the slickest ROM presentation I've ever seen, but then again if you're attempting to maintain a stock-looking distro, I don't think there's much more you could do. The tweaks are unobtrusive and integrate behind the scenes very well and this seems to be a fine piece of work.[xda-developers]