Here's my initial impressions of the Zenonia control scheme, after having played for a few hours (as an assassin and Paladin).
First, I was initially a bit reluctant to purchase this game due primarily to the virtual controller scheme. One of the primary reasons I bought a Droid was the physical keyboard. That is simply a requirement for me, I've never liked any of the virtual keyboards out there, and I've used an iPhone, BB, and several other smartphones on numerous occasions.
Everything else about the game looked promising though, so I bit the bullet and bought it (knowing I had 24 hours to try it and get a refund through the Market).
The virtual controller was initially more than a bit off-putting. It's become less of an impedance after a few hours with it, but it still gives me some trouble. Especially with the assassin because he moves faster than the Paladin. I occasionally find myself running off in directions I hadn't intended, running into areas or buildings I hadn't intended.
The auto-targetting works well and helps alleviate things, but I've had to adjust my playstyle to compensate for the issues I have with the controller. For example, I tend to let the enemies come to me instead of running after them.
That being said, I bought the game 2 days ago and I'm still playing it. The game itself is enjoyable and only marginally overshadowed by the control scheme. I would prefer a keyboard control scheme be added at some point, but I don't regret buying the game.