They're a great step up from basic clearos & evods; You can vape all the juices in them without worrying about cracking the tank and the coil heads are interchangeable with evods, plus they can be recoiled, what's not to like?
You might also want to look at the Anyvape Davide and the Aspire BDC, and if you have cash to flash, then have a look at the Kanger Aerotank (Myepack above) or the Aspire Nautilus - you should find all of these on the POTV Marketplace, or take a peek here for the Aspires & Anyvapes for examples and a good idea of what you should be paying. http://www.safercigs.co.uk/CLEAROMIZERS/cat705284_1944599.aspx