Got it!! Yesterday. We had it shipped to my wife's work address for safety. She said the box looked heavy.

LOL, what? Heh, heh, just the very reason I didn't get it. When I picked it up it was surprisingly light for its size, oh yes.
Packaging, fit and finish are all first class, as expected. So is the sound. To wit...
Bear in mind that this is part one of three. My plan is to eventually get two of these and a separate Little Mark III head. For now, though, it will be an extension cab for my Markbass 121H combo (single 12").
I began by sitting the combo on top of it. First I listened to the combo alone for reference. I have played many a gig with this combo. Then, I unplugged the 12 and listened to the 15 alone. The box is bigger than the combo box, so it was condsiderably deeper sounding. How deep? Not as much as I expected, but definitely deeper than the 121H. I also found that I could push the volume further through the 15 than with the 12. Not surprised at that, though.
So, then I put them together. This took my Little Mark II combo head from 300w at 8 ohms to 500w at 4 ohms. What a nice surprise. Granted, this is not the ideal mix of speakers, but the fullness of sound running two cabs with this combo, one of them being a 15, was stunning. Now, we all know that I will be limited by the 12. I won't be able to push the 15 as much as I could due to running out of headroom with the 12 first. And, I tested the limits to see how far I could go, just so I'd have some idea before gig time. Basically, running the eq flat, VLE and VPF off, and the gain at 1:30, I could run the master up to around noon and still play agressively and be safe. That's LOUD! But if I turn that VPF up much, the 12 will clank due to the boosted lows. Yet, even then, if I'm careful about not letting my hand plop down on the strings very hard I can get by with it.
Interestingly, I found that with the 151P cab alone through the LMII I could actually get about as much volume running at 8 ohms because the 15 could handle the lows better than the 12. I found that I could actually put the master all the way to 3:00 and the speaker would not fart out. That's just about as loud as what I had at 4 ohms with it at noon. Something like that. Anyway, it just shows what is possible with the 15. That was very encouraging to me, and tells me that I will LOVE two of these cabs.
Tweeter. Well, I'm not the best one to ask since my hearing is so bad. There is an attenuator for it. A friend was there who says he could tell when it was on or off. I could just barely tell. I'll probably run with it off, though.
So, I am pleased. I had read that this cab was not as deep sounding as some others. I guess that may be true, but the sound it does have is stunning, IMO. It's very tight and punchy for a 15. The low mids sing, and once I dialed in a tone I liked I can tell that this thing is gonna cut through the mix like a monster. So far, my favorite tone is: eq knobs all flat (except for high mids at 9:30 to make up for picking with long fingernails), VLE at noon, VPF at 8:00. I was able to push this sound to 2:00 on the master, not that I'll need to be that loud onstage, but just to experiment. The sound was pure tee clean even at that volume.
Markbass is some great gear. And the stack looks good, too (sorry, no pics, I don't know how to post them). Thanks for reading, I hope it helps someone else.
