I had a lot of trouble with him too first, but at my third or fourth try I used Hypermode in the correct moment, and then I could beat him within half a minute or so. So I say that if your using Hypermode wrong or not at all, Rundas can be a real pain cause he does a lot of damage, and it is difficult to dodge his attacks.

^^ What's the correct time to use hypermode on Rundas? I remember beating him on Veteran but it took me forever (like 20 minutes) and my fingers were hurting at the end. The good thing though is that I got really good at dodging all his attacks.

I think I used it the first time when I could take his shield away, then I fired at him so he lost a lot of energy, and when you do it correct I think you can stay in Hypermode to weaken him until you can take his shield off a second time and then you can destroy him completely. I only know about normal mode though, and I'm not even sure if I didn't go into Hyper twice to beat him completely.
Anyway, I think it would be a waste to go into Hyper before he lost his shield, but once you are in, you should try to stay in as long as possible.

On another note, I ran into Ghor today and I got to say that he was very easy to defeat. I haven't seen a difficult boss for quite a while now, and I definitely have to say that Prime 3 is the easiest so far.

The correct time is at the very start of the fight. When he's stunned, wait a few seconds  before ripping of his armour, so the corruption kicks in. Then kill him in one hyper mode. Shouldn't take longer then 20 seconds with some practise. Oh, and I'm talking hyper mode difficulty.

I never played normal mode lol, I started on veteran mode right away and metroid prime 3 was my very first wii game. It still was pretty easy, but I died sometimes probably because I'm a lefty.

Metroid prime 2 was really hard in bosses, but also in finding your way through the big world, solving the puzzles and finding all the keys. Metroid prime 3 was way too easy in those aspects. Still a fun game never the less, but I was kinda dissapointed.

Im talking the very first time on Hypermode. That move where he creates a huge spike of ice and throws it at you, taking quite a bit of energy. After a while you learn the groove and can beat him easily, but at first its difficult.

Personally, for me, I found the Metroid Prime series reasonably challenging. By that I mean, I never really had any problems against any bosses besides maybe Metroid Prime at the end of the first game, but Metroid Prime 2: Echoes and Metroid Prime 3: Corruption I found rather easy. In contrast, I can't get past Norfair in the original NES incarnation of Metroid. Metroid: Zero Mission was fairly simple until it came to Kraid, Ridley and Mother Brain... Mother Brain in particular is hell in Tourian. I haven't fought her in Super Metroid, but Metroid: Zero Mission's addition of an attack (whereas before she'd remain static) combined with the (annoying) turrets and relentless Rinkas has changed my view about videogame difficulty entirely. Once you get used to the control scheme in Metroid Prime 3: Corruption (if you've played the first two and are used to the GameCube control scheme that is). Although, in order to get everything in the game it is challenging, but even on the hardest difficulty in Metroid Prime, Metroid Prime 2: Echoes and Metroid Prime 3: Corruption, I didn't have too many problems. 

Personally, for me, I found the Metroid Prime series reasonably challenging. By that I mean, I never really had any problems against any bosses besides maybe Metroid Prime at the end of the first game, but Metroid Prime 2: Echoes and Metroid Prime 3: Corruption I found rather easy. In contrast, I can't get past Norfair in the original NES incarnation of Metroid. Metroid: Zero Mission was fairly simple until it came to Kraid, Ridley and Mother Brain... Mother Brain in particular is hell in Tourian. I haven't fought her in Super Metroid, but Metroid: Zero Mission's addition of an attack (whereas before she'd remain static) combined with the (annoying) turrets and relentless Rinkas has changed my view about videogame difficulty entirely. Once you get used to the control scheme in Metroid Prime 3: Corruption (if you've played the first two and are used to the GameCube control scheme that is). Although, in order to get everything in the game it is challenging, but even on the hardest difficulty in Metroid Prime, Metroid Prime 2: Echoes and Metroid Prime 3: Corruption, I didn't have too many problems.

Sorry for double post.

I'll admit I had trouble against that attack when I went through on normal mode... because you can't dodge it once he throws it.

When on Veteran though I learnt to shoot it at the base so it breaks.

The Prime series is indeed quite hard. I'm hoping that for Other M they either ease up on the difficulty or it has that feature from NSMBW that helps you along.