Yes, the Blackstar is awesome. For $299, I'd go for it. I will say that the cleans are not up to what I can get out of the Mesa Roadster, but at $2000 + the cabinet the Mesa should sound better. They are not bad, but just not great. There are better amps for that. The Blackstar does have a real nice overdrive/distorted sound when driven hard. I can get the sound I want at bedroom levels, though like all tube amps it likes to be driven hard. 5 watts can get very loud, believe it or not.
I tend more to the classic rock style of music - AC/DC, Led Zeppelin, ZZ Top - which might have different requirements than metal, but the Blackstar is sure to impress just the same. Give it a try. If nothing else you could probably still get your money out of it if the sound isn't to your liking. I haven't seen a lot of them at the stores so far, and the combo I bought is the only one I've seen in my local Guitar Center.