I migrated from huawei ascend mate, huawei's flagship, 1.7ghz quad core, 2gb ram...consider quite smooth oledy.
The 1+ spec is among the highest in the market, so, very smooth but certain opening apps i.e. WPS Office excel bit lag (not my unit have problem, I believe is overall android

) so I m really asking alot there
Durability wise I think these guys are mentioned the back cover of sandstone, the texture will peel off over time so might need your average TLC (tender loving care), bend strength should be up there among the stiffest or toughest....and some x-evidence of water proofing ability. So durability is abit mixed bag of beans. I put the silk white original back casing to my sandstone so getting the best of both worlds.
Battery life is another dept liek performance that exceeded my expectation....The performance part I'm quite satisfied already, expecting more from it is asking alot from android set current (technical) ability which I believe is android's own limitation...in other word, the set piece performance is really *that* good. Probably much thanks to the cynogen guys.
the 1.7G quad huawei ascend is a huge 6.1, and 4050mah, a monstrous battery....can clock SOT 7-8 hours no problem has still got enough juice for the rest of the (quieter) evening. not expecting the 1+ to match but it totally gives more than enough battery not just after work but till before bedtime... can SOT 6hrs without breaking a sweat. Maybe lately abit quiet at work, I can still remain 40-50% battery after 5pm with SOT 3-4hrs. (I'm on powersave & balance)
So all in all, the phone really did a fantastic job, more or less exceeded all my expectations (marginally).
I would summarize it in the most appropriate quote for it, like the Razer gaming peripherals product.
1+1 is passionately made for smartphone enthusiasts, by smartphone enthusiasts (including cynogen).