The only problem I had with the Landmaster was when shot at close range. I didn't realise it dealt damage to the tank and the pilot inside as well.
Other than that, I found it to be a very effective vehicle. The slow rate of fire is balanced by high firepower, as it stronger Aparoids as well as turrets in a single hit, which neither the Arwing or Pilot can do. This is important in missions where lots of strong Aparoids are about, since the time it takes to charge a blaster will deplete your combo gauge.
When getting swarmed by a group of small Aparoids, you can run them over without taking damage, which is much more effective than shooting everything one at a time, not to mention that if you get swarmed, shooting them may damage yourself if the enemies are nearby.
The Landmaster is very effective against the random aerial enemies flying around, especially on Sauria. When your cursor highlights an enemy, it's pretty much a guaranteed hit, even on a moving target. The Landmaster actually shoots off target into the space where the Aparoid will fly towards. This is pretty effective in maintaining a good combo on Sauria, as well as a good way to deplete the might gauge without having to switch vehicles (in which case, will consume time and destroy your combo). The airborne enemies also don't return fire when you are in the Landmaster whereas they will chase you when you're in the Arwing.
As far as single player goes, the Landmaster is pretty useful. In multiplayer, I'm not sure whether the ease of hitting airborne foes applies, and I'm quite sure the Landmaster remains unable to dodge lock-ons unless it's taking cover under a structure of some sort. I've still got my doubts to using Landmaster in multiplayer.
As for controls, the only thing I didn't like is the inability to move forward/backward while turning using the single stick. You can do it with the dual stick control setup, except that benefit comes with a disadvantage of it's own - the immense difficulty in sidestepping into a corridor and aiming upwards to blast a laser turret when on foot. The needs you to use the Control Stick, L, R, and the C-Stick, and it was pretty hard for me. I didn't even bother with the third setup because you can't run backwards. I didn't mind too much though, because when I gave it a little thought, if they mapped sidestepping to L and R (so you can sidestep left/right while moving backwards), then camera would have to be the C-stick - and it's pretty hard to use the C-stick and the A button at the same time to aim and shoot, since I'm sure we all have one thumb
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I was a little worried when many people had complaints with the Landmaster, fell off high altitude frequently, and had trouble performing the sidestep - I guess they were tense when they played, so they found it hard to avoid pressing L all the way down. If you're good with controls though, you shouldn't have any problems, and if not, you'll get used to it. I never had any problems myself, which is probably why I enjoyed the ground missions.
On another note, most of the multiplayer songs are quite poor
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Go figure...