Summing it up, he also feels that the audience for the Lumia 620 might be found as the 'taster' second device:
What's more, it's arguably more attractive than most Google-powered phones around the same price point and could prove to be a huge hit among smartphone beginners. There's also a good chance that the more-gadget obsessed might pick up the Lumia 620 as a second device to give Microsoft's mobile OS a try -- and with compatibility on two US networks, it might be worth an import. It delivers real-world performance as good as Windows Phones that cost more than double. If anything, it's making us reconsider whether those other rivals are worth the extra outlay.
More than the Lumia 920 or 820, the Lumia 620 is going to be an important handset for Nokia and the Windows Phone platform. It has enough specifications to run the OS with a decent level of performance, and has enough storage and expansion via MicroSD to make it a viable phone for third party apps (unlike the HTC 8S, but more on that in an upcoming AAWP review). From the reviews starting to come in, the Lumia 620 has certainly got the critics on-side.
You can read the full review over on Engadget.