I'll try to address the points raised in the article...
Bundled apps : Nokia hasn’t come out with any ground braking apps. May be this happed due launching phone in hurry. But who cares ? Android and iPhone has much larger choice of apps.
Quality or quantity? Pretty much all the big apps have now made their way to the marketplace. Some are still not here, but don't doubt that they won't eventually arrive.
This person is knocking the Nokia Lumia due to the growing WP7 marketplace. That being said, Nokia have released their own Music app and Nokia Maps free of charge for their WP7 devices. Kudos to Nokia.
Display : Its display is much dimmer other devices and even from Nokia’s own N9. So this reduces overall charm (and see what if you are walking in Sun Light ? )
Totally disagree with this. It's vibrant and colourful from it's bezel to the display. The WVGA AMOLED screen also adds depth and clarity. I was totally impressed with the display.
Camera Quality : Even Nokia known for best Camera Quality phones it doesn’t seems promising this time with Lumia 800. Many Android devices are ahead of this even its own N9 device.
Some Androids maybe marginally better, but that is no reason to think the 8MP Carl Zeiss camera lens is anything sub-par. Further more, I wouldn't rule out a possible camera tweak in future updates.
Battery Life : Almost everyone love good battery strength. Although its battery is quite promising but it still losses race taking other Android devices out there.
Nokia are going to release an update to help battery issues. You would have thought this Android fan was used to poor battery life.
Front Camera : Oh my God!!! Who in the world told Nokia not to include Front camera even users have loved this feature in Nokia’s featured phones. And not having Front camera takes it to no Video call device and again dips its capability.
Ohhh shock horror!! Honestly, I have zero need for a FFC, even if it becomes the norm for all Windows Phones. I guess you need to ask yourself if this will effect you.
No memory card slot : So no storage external storage option like other devices .
Nope. Windows Phones don't support this function. I can't say I miss it though.
Weak Browser : As it doesn’t support Flash or Silverlight (oh yes no Silverlight even)
IE9 is far from weak. Flash is dying and causes a lot of issues for Android. I have it disabled on my PC browser. My user-experience hasn't really been that hindered with no Silverlight. What I have noticed is the ridiculously fast browser with the native HTML5.
No USB mass storage : Only file management option and sync pass through Zune.
Why would you need it with Office, Skydrive, and Zune?
Speakerphone and Audio : Comparing with devices Samsung I9100 Galaxy S II, HTC Titan, LG Optimus its quality is below average.
Unfortunately, I can't vouch for this, but I question the credibility of this blogger over the other points raised.
The Windows Phone 7.5 OS is the biggest selling point of any device, IMO. The OS will integrate all the areas of your social and professional life, making it a pleasure to use. The marketplace is still young, but it's currently the fastest growing against the competition. Personally, I love it the more I use it... when you realise the bigger picture - the MS ecosystem with the use of Office, Skydrive, Zune, Xbox Live, Windows Live, etc, I'm sure you will too.