I've got a Malt 2 and would agree that you get a great bike for the money - mine was only 550 so you may want to upgrade the frameset or some of the componentry. Knocks the socks off a similar priced rock hopper - better quality bits and rides better. It's also assembled in Britain so you can feel good about yourself!
I had no problems with mine. Give Merlin a call and see what they say - if it's really bad then they should do something about it or pay for you to take it your local bike shop
Agree that the Malt 2 frame is better than the Malt 1 frame.
I've got a Malt 2 and had it nearly a year now - it really is a nice bike - feels just right and gives plenty of confidence. I'm 6'4" and also went for the 19" frame - beware though - the sizing of the Malt 1 and 2 is very different.
Only point worth mentioning is that if you are fussy over exactly what bits of finishing kit go on the bike (bars, stem, seatpost, tyres) then spec them exactly - Merlin will often mix and match a little depending on what they have in stock I guess.
The other thing - I had an early MX Comp 04 fork and it was full to the gills with oil and therefore was a bit pants. Apparently the oil levels should be right now though.
They don't seem to feel floppy, rattle or plain loose although they do seem fractionally less tight then on my girlf GaryFisher bike. I'll also check out the wheel skewers and QR as a couple of others have mentioned those too. They suggest lubing the skewers - any ideas as to how I do that?