Looks like I've gone Leica mad!
If you've read anything about the Leica M8 on the internet you've undoubtedly heard about all of its "issues," so I won't bother going over them to any great extent, but I will add my thoughts on them.
The shutter is louder than a film Leica, no doubt about it, but it's not really loud either. I'd agree with what some people have said about the shutter making a different kind of noise, but honestly it's as loud as pretty much any DSLR these days. Of course, there are a couple of advantages to the noisier shutter in the M8 versus the quieter one in the M9, M8.2 and so-called M8.1, such as 1/8000th second top shutter speed and 1/250th flash sync. In a professional-grade camera, I really appreciate the higher flash sync, so I'll put up with a slightly noisier--but not really noisy--shutter.
One thing that really bothers me: why no PC-sync port?! I know a lot of people say, "oh, well a M-rangefinder is about natural light shooting," but that's stupid. Photography is about controlling light, whether it's existing or not, and sometimes I'd like to be able to plug some studio lights into the camera and still be able to use the shoe for additional viewfinders. I can't believe the M9 still doesn't have a PC-sync port.
The camera itself is really rather unobtrusive--it's smallish and it looks like something you dug out of your grandpa's closet--unless someone happens to recognize it as a Leica. It's sort of funny to watch people process why an "antique" camera like this has an LCD on the back, and inevitably they ask, "Is this digital?" I've always wondered what they'd think if I said no.
I sort of have mixed feelings about removing the bottom plate to change the battery and the SD card, but it's not too much trouble; I know some people think it's a bother, but it is what it is. Battery life is as you've heard: on the low side. I usually take my M8 on vacation with me and I'm always careful to charge the battery every night; I'd like to just carry an extra battery pack, but they're stupidly pricey. I'd guess about 400 shots to a charge when you're not doing a lot of image review.
It has a 1.33x crop factor compared to 35mm film, and that's a little annoying, but to me since it's a rangefinder and you're not actually looking through the lens it seems easier to me to adjust to than the 1.5x or 1.6x common to most DSLRs. I would still appreciate a full frame sensor, but the M9 is just more than I can honestly justify spending on a camera (and sometimes the M8 is as well). I sold my Voigtlander Color-Skopar 35mm f/2.5 PII and replaced it with their Nokton Classic 35mm f/1.4 MC, and I'm fairly happy with it as a basic "normal" lens, and it wasn't too outrageously expensive.
The general conclusion on the internet is that the M8 is too noisy regarding higher ISO settings. And I'd maybe agree, but while it's no D700 or 5D Mark II, it's also an improvement over most APS-C DSLRs out there. Noise aside, I've worked with files from a lot of different cameras and the M8 files have a crispness that I haven't been able to find in other cameras, and I'd wager that the lack of any anti-alias filter in the camera is the reason. I've compared the M8 against the Canon 7D, and I'd conclude that, in terms of resolution, the M8 is a match for the 7D. A camera like the 5D Mark II has an advantage at large print sizes, but I think up to 11x14 or so the M8 is a strong contender.
IR/UV sensitivity is an issue, and the whole black-into-magenta thing shows up pretty easily. Leica sent me two filters to block it, but even with coded lenses the whole cyan corner shift is still a bit of an issue at times. I've coded my lenses with markers, but my Zeiss and Leica lenses rub off too easily. Voigtlander lenses have a nice groove in the mount to prevent the self-coding from wearing off, but I tend to favor Zeiss lenses, and I find myself recoding them every four or five lens changes. But having an infrared sensitive camera is actually pretty nice, and a simple Hoya R72 visible light blocking filter is all that's needed to take advantage of it. The best thing is that unlike on an SLR, focusing (and metering even!) is as easy as ever.
I actually sold off nearly all of my Canon kit in order to purchase more M-mount lenses. I thought I'd keep the Canon stuff for the things that a rangefinder isn't suitable for, but it turned out that for what I was shooting a rangefinder could do 90% of it. One thing that turned out to be pretty neat was that when I put my Canon ST-E2 wireless controller on my M8, I found out that if I used the 580EX II Speedlights set in manual wireless mode I could fire them off with a maximum sync-speed of 1/90th second! I just had to make sure that the M8 wasn't set to second curtain sync or it'd miss the flash, but I was surprised that this worked at all. In the end though, the 580s were sold and I've picked up some Nikon SB-24s that work great with the M8.
Anyway, I really like the M8, but it's not a camera for everyone, and there's times that I really miss having a DSLR. Having such an anachronistic camera is always going to be a bit of a struggle unless you're either wealthy enough to not really care about it, or have a specific enough shooting style that you can make the most of it. I wouldn't really say that I'm either of those things, and I'd probably be better suited with a camera like Sony's new NEX-7, but every now and then everything comes together correctly and the M8 is the greatest camera I've ever used.
Examples (not necessarily of greatness):