Pros: - All the features you'd come to expect from a flash card now and more.
(DLDI auto-patching, real-time save, slow-motion, etc.)
- Good Build-Quality.
- Supports the M3 Sakura firmware which I think is easily the nicest menu you can currently have on a DS flash card. Nice fully-skinnable sliding interface.
- Can dual-boot M3 Sakura firmware and the regular "TouchPod" firmware.
- Through M3 Sakura, you can run many media file formats and ROMs in the same loader.
- Both firmwares are still being updated regularly for game and bug fixes along with new features.

Cons: - The normal "TouchPod" firmware is very slow.
- M3 Sakura doesn't have great homebrew compatibility, but you can always just dual-boot into the TouchPod firmware.

Other Thoughts: I've owned my M3 Real for more than a year, and it's my favorite flash card out of all the ones I've tried. (About five slot-1 cards and a few slot-2's.)
I'd say that the CycloDS is the most functional card you could get, although it has it's faults here and there. However, the M3 Real has the nicest and most functional firmware(M3 Sakura). You can read text, play music and movies and view pictures once you turn it on without needing to boot any homebrew, as well as loading games and homebrew.
It also just looks the best, being skinnable and it has a nice sliding interface, making it even quick and easy to get to files.
I haven't yet been disappointed by this card since I got it.
Also, no issues with memory cards so far. I've tried a 1GB SD, 2GB SD, 4GB SDHC and 8GB SDHC and they have all worked fine, in case you may be concerned with that.
Oh yeah, rumble pack isn't great, though. It's fine, but not great. I gave mine away.

Bottomline: Buy it if you want a reliable, good impressive card for DS that's still being updated. I think it's the best choice you could make.

Pros: Had this for a year now, and it's still going strong. No problems with build quality or any intermittent software issues. Exactly the same as the day I got it. Have had occasional problem with a rom not loading but that was fixed by updating the firmware on the card which is very easy to do! So it's been really problem free! Would not hesitate to recommend especially after long term ownership of this item.

Cons: None, although I haven't tried an SDHC card on it. My 2gb non-sdhc card has sufficed over this time.

Other Thoughts:

Bottomline: Good DS Card!

Pros: - Good compatibility with games
(e.g. can play Made in Ore and R4 cannot)
- Works with all games I've tried
- Micro SDHC compatibly
- M3 Sakura firmware
(latest and most updated firmware/loader)
- Bonus: Rumble Pack and Card Reader
- It is real easy to use after you set it up

Cons: - Cannot play some trimmed ROMs
(can be played on M3 Simply though)
- Could be cheaper
- Does not come with CD or any instructions

Other Thoughts: If you need to find firmware, go to
http://www.linfoxdomain.com/nintendo/ds/
You can put M3 Sakura firmware on your DS, which looks WAY better than the M3DS firmware AND ...
http://img41.imageshack.us/img41/333/24260871.jpg
Your microSD should look something like that
I wish it was cheaper :)

Bottomline: This is a really good deal for something so good, so BUY IT IN BUNDLES AND SAVE MONEY!

Pros: Plays all the games so far, easy to find and play movies. Great product for great price. Just use tutorials on youtube and other sites to set up system and its easy, plus the price went down even more than when i bought it. Works great with sdhc and the usb reader is easy to use.

Cons: the new dsi is coming out, and i haven't played a sports game that i really like yet. Could use more mario kart games

Other Thoughts: Just use tutorials on youtube and other sites to set up system and its easy

Bottomline: wish i had another ds to get another