I was asked this yesterday, and the answer: Yes I am, and I am satisfied with it, but it is not without issues. 
2 weeks in and I can report many good things and some less than good.
* Hardware. The phone looks nice, feels solid, the AMOLED display is beautiful, the camera is fine, this is a quality piece of hardware. I certainly don’t feel bad in anyway about giving up my iPhone hardware. I’ll be in LA in a little while and have an LTE network to use it on, and at that point I may say that the Lumia hardware is definitely better.
* Hardware accessories. The lack of compatibility with existing iPhone earbud/mics, the paucity of other alternatives, this is a problem.
* The OS. Very solid, looks nice, has some real innovation. The ability to pin content to the homescreen and to see integrated photos/updates from my closest family members is nice. The core OS seems fine.
* Bundled apps — mail, calendar, maps, dialer, ie. Very much a mixed bag here. The apps feel like they need another iteration or two. My mail inboxes should be automatically combined. When I compose a new message, use my default mail system, don’t make me pick. IE has some repaint issues on drag/resize. Calendar lacks a week view. Contacts seems buggy/wonky at times — lost a picture for one contact, another contact is just impossible to find. The apps all look ok but they need another round of usability work.
* Marketplace. Too much real estate given to things that no one uses — podcasts, ATT, Nokia. No strong merchandising. MSFT really needs to ramp this up. Why doesn’t the first screen of the marketplace show me the most popular apps I don’t already have, and the best apps for me based on my existing apps? And podcasts? Seriously, am I missing something, is there a huge base of podcast users? Is WP trying to be #1 among the podcast crowd?
* 3rd party essentials — Evernote, Adobe Reader, WordPress, Facebook, Twitter clients, RSS, Amazon, etc. These are all there and they work fine, I can get my job done.
* 3rd party inessentials — games, photo apps, etc. A significant significant weakness area. No Instagram, but apps that are kind of like instagram. Very thin on the hottest games but clones that are like them. No Draw Something but a WP-only clone. Very very weak.
* Cloud. With no native Mac support, I can’t get too excited about Skydrive. No iTunes Match like syncing of music. I’m no big fan of iCloud either to be honest.
* Dev Tools. I’ve “written about this already”:http://theludwigs.com/2012/04/when-you-are-10x-behind-in-mobile-apps-your-tools-probably-ought-to-be-10x-better/, MSFT is not helping themselves at all — too hard to sign up for the program, too much VS crap to wade thru to just focus on phone development. I have created a few toy apps, the tools seem to work fine once you get there. Game development seems more complicated than it should since XBOX and WP development is commingled, this doesn’t feel like a wise commingling to me, but maybe some of the casual game writers love it.
OK so I net out with a decent phone and OS, but a lot of issues in all the surrounding pieces. I’m OK with the phone but it certainly seems like MSFT has to do much more to get to the strong #2 in the market, to be Pepsi to iPhone’s Coke. If you get one of these you won’t be unhappy, but there isn’t enough there to really compel anyone to switch from an iPhone or to get instead of an iPhone. And if the word on the street is true, that I won’t be able to update the Lumia to Windows 8, well, MSFT will kill any goodwill I have towards the phone.
