It's almost on par. Feature-wise, it's almost there. But like others have said, Windows Phone has to be better. Especially to convince iPhone users, who are very often either religiously zealously attached to their iPhones to the point of praying to Steve Jobs at night before bed, too uninformed to know that there is another smartphone aside from iPhone, or won't switch until they believe it's 'cool' to do so.
From Build, we see that we have week view, Cortana, in-car integration being worked on, and lots of other little features. This is definitely good news. Though Windows Phone does need a few extra things, such as location-based reminders (Cortana might do this, but a Cortana-less way to do reminders should be available), HDR photos should be enabled on every Windows Phone, zoom-out with mini-thumbnails of your images (see iOS7) vs. the little bars you get by tapping the date, when sharing a pinned location, it should auto-open in the default mapping app on your WP (now it just sends a text with 'check out this place') when you click on it; now it's just a little text message with no difference from any other text message. I could go on, but just check out reviews of iOS7 and the most recent Android to see which features could be added.
I would still like to see some 'niceties' such as parallax motion backgrounds on the lock screen (look at Zune HD, which had this on its home screen), motion weather apps on the lock screen over the lock screen back ground, playlist editing in XBMusic, restoration of Zune in place of separate X-Box Music/Video/Podcasts (Hubs are much nicer than the separate apps. I've used both.), add 'places' in the Pictures hub to view pictures grouped by place (instead of getting rid of the picture hub concept like it appears we get), move Cortana to tap/hold Start and restore contextual search within apps, and add tap/hold search for Bing Search, alphabetized settings (what order are they in now?), and adding share-to to share an e-mail, song, album, video, tv show, website to a friend nearby (iPhone has this).
What I would like WP to avoid is the removal of the camera button, the lack of microSD, and the continued use of capacitive buttons. Capacitive buttons are always the cause of accidental presses, whereas if we had physical buttons, this wouldn't be an issue. OEMs continually give us limited memory (16GB in 2014? really?) instead of including microSD for expansion. A Camera button sets WP apart from the other two OSs, and should always be required.
The Windows Phone app in Windows 7/8 is still horrible, as is X-Box Music and X-Box Video. Zune and Windows Phone 7 was much much better. Using iTunes with iPhone is a better experience than what Windows users have today. I would like to see Microsoft restoring Zune, use that for purchasing apps in Windows Phone and restoring it, along with movie/tv/music/podcast/audiobook loading/browsing/listening.
Short version: It's really closing the gap. But the perception gap really needs work. A lot of people are terribly uninformed an even when you show them Windows Phone being better, they forget 5 minutes later. You need more advertisements to tout the new features.