I cannot speak highly enough about this bike bag! TL;DR: If you don't want to shell out the money for a hard case, this is the best value soft bike bag available.
My bike: 48" Kestrel Talon (Triathlon config)
Inside: The biggest concern with any soft bike bag is whether or not it will protect your bike during its journey. This bag has thick (0.5"-1.0") padding on all sides. There are plastic wheel protectors that protect the spokes and axles for both wheels, and two specifically shaped pads to be wrapped on the bike itself (one for the derailleurs/chain, and one for the top tube/down tube). There are adjustable Velcro straps in all the right places on the inside, and more pockets than I knew what to do with. One of my favorite aspects is that nearly the entire inside is covered in a gray tarp-like panels that can be detached (Velcro), hosed off, cleaned and reinstalled like new. My bike is small, so I cannot speak to larger frames, but there was plenty of room int he bag to fit a Joe Blow tire pump, a folding chair for my significant supporter, helmet, foam roller, tools, and nutrition.
Outside: When rushing to grab hold of the bag, no matter where you reach there is a reinforced handhold waiting for you. The bottom has several thick plastic sliders which seem to stand up to any dragging abuse, and the back two wheels are wide enough to be stable, and solid enough to handle even the most aggressive concrete. The canvas on the top/sides isn't waterproof, but light/moderate rain for short periods of time was no problem. The bottom-most red panels are coated, and to the best of my knowledge, waterproof.
Con: The only downside to the bike is that it is on the heavier side (almost 20lbs) but for the durability and padding, I'll take the extra weight any day.
Things I did that did not come with the bag: I wrap my handle bars in bubble wrap to prevent any pinching on the cables/rubbing from the stem to the frame; also, I place one of the forks through a hollow foam roller to prevent potential crushing. I honestly believe the bike would be fine without these precautions, but since I love my bike with all my heart, I don't mind being overly cautious.

Just back from my first (very long) international trip that included 3 connected flights with my carbon bike and happy to report no breaks, scratches, or anything noticeable - held up better than I expected. In fact, saw many at the race I went to with the same bag which was definitely comforting. The only minor annoyance is that the bike doesn't fit quite as nice as I was hoping. For example, I have a medium (56) bike and if I use the fork pads and strap the bike in, the gearing doesn't sit well on the pad provided and there is a lot of empty room towards the back of the bag. Also the wheel wells for my rims where a little too tight and I was nervous it would bend my disc brakes - which luckily it didn't. Overall thought pretty happy and won't hesitate flying with it again. If it helps I also used lots of bubble wrap around all parts of my frame and filled in empty space with packaging materials.

I bought this as an alternative to the heavier, hard sided case that I've used several times, and after renting a similar, soft-sided Thule bike bag. I've used this bike bag four times, two RT airline flights. The Speed Hound worked well, easier to pull around than the bike box. Also doesn't invite heavy suitcases to be stacked upon it as a bike box might. I was able to pack & strap my disassembled bike in this bag, but wish it had come with a sheet of directions, for its best use. The Speed Hound bag includes a very handy chain guard which the Thule bag did not. Also a padded wrap to go around the front part of the bike frame possibly for scratch protection. This brand lacks a few niceties of the Thule bag, in particular the stiff inserts for the ends, integrated front fork skewer tie-down, and a couple extra adjustable straps with clips for securing the bike to the bag. All in all though, a good value.

The Speed Hound experienced her maiden voyage this week, coast to coast from Charleston to San Francisco. First, the product arrived exactly as advertised. I was able to pack my Trek Madone (with integrated seat post) easily into the bag and also brought helmet, shoes, kits, tools and a full sized floor pump along. The bike arrived in perfect shape, TSA even rummaged around in the contents and they did not disturb the tie downs etc. The bag rolls well, and was easy to handle even lugging it on and off the rental car shuttle bus. Definitely a great purchase and I would recommend this to anyone traveling with a bike they value.

This bag vastly exceeds expectations,and my previous experiences with "soft" bike bags. I often found that the convenience of a soft bag was outweighed by the lack of protection provided; one of my bikes ended a flight with a broken frame! No such worries with the Speed Hound; its protection, including wheel discs and drivetrain cover, protect the bike perfectly. At the same time, the bag is light, easy to carry, and stores compactly. I also appreciate the color scheme (mostly black) as bike bags will collect dirt pretty quickly, and some of the brighter bags look pretty dingy after a bit of use. The packaging was first rate, and the bag is a breeze to set up/pack your bike in. Overall, I am seriously impressed with this bag and cannot imagine going with another option on the soft bag market (nor going back to the hard case style).