I've had my 2013 Nexus 7 for about a week now - it's my first Android device ever after having all iPhones and iPads. I currently own an iPhone 5S and just sold my iPad 3 in anticipation for the new model this fall.
Trying to be fair assessing it, my initial thoughts are:
Build quality is pretty solid. A step down from the iPad Mini, but it's still "good." Definitely feels solid and does not feel cheap. I hate the off-center front-facing camera, though. Without a physical home button, it's easier to grab the tablet in the wrong orientation and struggle for a sec to find the power button.
The screen is phenomenal. Absolutely up there with the best of them - which I would argue are currently the iPad 4, HTC One, and PSVita. Lots of color, super sharp, more-than-acceptable blacks. The whites are a bit tinted, and the blacks shadow a bit in dark scenes; but it's still an extremely competitive display.
The hardware seems plenty fast. There's definitely a slight hesitation or "judder" when scrolling a webpage or using pinch-to-zoom. On the home screen and whatnot, it's not an issue; but when browsing the internet for example, it's not bad, it's just an immediately apparent step-down from what I'm used to. So I don't think Android is a "sluggish mess" like many argue by any means - but I can see how it's not quite as smooth as what I'm used to - and it is a bit distracting since internet is the biggest reason I use a tablet.
The App Store seems plenty robust. Yeah - there's a couple things missing; and new stuff seems to release on iOS first sometimes. However, there's a lot to choose from - and so long as you're not someone wanting the newest apps 100% of the time and downloading stuff every day, you'll be fine.
I still don't see the allure of widgets. Maybe I'm missing something or need to give it more time - but scrolling through an email widget or looking at the weather isn't harder than swiping down my notification center. Having a calendar or something is okay I guess, but it's not like clicking an App icon is hard or anything. I think it would be a bigger deal on a phone, where you use the device to get small bits of info very quickly. But on a tablet, I'm usually sitting down with it anyway, so it's not much of a need at all.
The form factor is .... .... surprisingly great. I use a full-size iPad, and I really couldn't ever give it up as I use it for travel a lot. And so when I'm in a hotel room, I want a bigger display for browsing the internet. The iPad provides that, and I don't see any reason I'd be willing to give that up. However, if it weren't for travel, I really love the "grab-ability" of the 7. It's just "handier." More like grabbing your phone than your laptop - I can throw it in my backpocket if I need to, so I never HAVE to carry it in a pinch. It's not a device where I must consider bringing it with me... I just can. Event the iPad Mini isn't good enough for this. So, again, it's not right for me - but I can definitely see the allure.
Only thing that I'm actually "disappointed" with is the battery life. Most reviews say it's really good - but I'm burning through about 20% every hour and a half - making for about 7 and a half hours at medium brightness. And it loses about 5% charge each night, if not more; where as my iPad lost about 2-3% over night. It's not BAD - but I was expecting comparable or better to my old iPad - not worse.
Overall though - the price is a huge factor. I think my impressions are "just a notch or two down from the iPad" - but it's less than HALF the price. That's a huge bulletpoint; and so for most people, I think I would recommend the 7 if money is a concern and/or they want a smaller screen.
