I had the Lenovo A1 for about a year and a half before getting the Nook HD+
I never had an issue with durability on the Lenovo I even passed it on to my daughter and it is still working.
Comparing the two is kind of tough as it was 7inch vs the pluses 9inch. I am still getting used to the larger form factor the Lenovo was easier to cart around but I definitely wanted a larger screen to make reading easier. I think I am going to return the Nook case I bought and get something different, something less slick so I don't drop the tablet. Overall I like both we will see how I feel with the plus in a year and a half that will be the deciding factor on if it is a hit or miss.
Thanks for the reply...and here's my 2 cents on covers since you are looking for one!
I bought the Jonathan Adler red case. I highly recommend it. It's well worth the money. I take my Nook EVERYWHERE with me - it's pretty much an appendage now. Sometimes its in my pocketbook, sometimes it lays on the on the floor of my mini van, sometimes I just carry it around. I truly hate to think about what my Nook would look like today if i didn't have this cover. I've had the cover about a year and a half and it barely looks worn. If the cover gets a little dingy, i just wipe it off with some windex.