I'd call it SOLO 0.9 beta.... Disappointed as most are, I own both SOLO and P150 and would buy them again over SOLO II any day.
I see 3 improvements:
1. 120mm intake fan
2. USB 3 - that is more of an update than an improvement, but still welcome.
3. Tray cut outs for cables and backplate (more of a must have now that the bottom of the tray is blocked all the way to the front)
Then I see quite a few things that could have been improved but were skipped in the name of cutting corners (not like the old Antec to do this)
1. Same power button with ~50% chance of breaking.
2. Similar support bar for the PSU - you'll need to take it all out to swap PSU, and yes I had to do this a few times of a few rigs and its just a pain.
3. Same hard to reach filter placement.
4. Same polished black finish when everyone knows matte is much cooler! not to mention cleaner. And no white (someone call marketing and tell them chicks love the white cases)
And to top it off there are a few new flaws that make this case much less desirable
1. Less HDDs with only 3 trays or 2 suspended! that is more like a mini or HTPC offering, not a midi tower. This one is the true deal breaker for me! will not buy this or recommended this case to anyone because of this flaw. people need more hard drives.

People that buy super long GPUs will never buy a Solo case. EVER! removing 3 HDDs will not change their mind. It will simply give them yet another reason why not to buy a Solo case.
2. Less 5.25 space and a slot load? Are Antec selling these drives with the case? If not where do I buy one? don't bother I wont be needing it
3. Only one intake fan frame - at least the option for filtered positive pressure would have been a nice touch.
4. Less room behind the mobo tray (or so it seems)
At least the P280 is looking better, even if they did drop the chamber concept and go with a CM 690 style configuration.
Antec aint what it use to be...
I still think P182/180 and P150/Solo were the best cases Antec ever made, and its been down hill since.
Even the One Hundred it not as good as the Three Hundred.
Whats going on Antec?