I feel that I have to dispute the largely negative critique of the game that Darius75 presents. Pikmin is one of the first games for the Nintendo Gamecube, and was created under the close guidance of Shigeru Miyamoto (at least, closer guidance than some games attributed to him). Although it is by no means a perfect game, it does achieve at least some of the goals that it sets out to, namely being completely accessible (remember that Nintendo's first party efforts, while often criticised at face value as being 'kiddie', are intended to be accessible to players of all ages and skill levels), highly original, and a good use of the new hardware, both in terms of graphics and control as well as game structure. It would be hard to imagine Pikmin being possible in technical terms on any of the previous generation of consoles, even without taking into account the more extreme graphical niceties. But most importantly of all:-
Pikmin is not an RTS.
To compare the game to something like Warcraft is like comparing chalk and cheese. There are practically no points of common ground, and those that are identifiable do not share the same purpose in Pikmin as they do in a conventional RTS.
The game's combat is not about AI. The enemy's advantage is not their facility for strategic planning, it is rather the advantage used by nearly all natural predators: size and strength. Only by combining the abilities of the individually weak Pikmin can they be overcome. There may not be much strategy involved in this, but there is a sizeable amount of skill. (I refer players to the battle with the giant mushroom thing in the Forest Navel level for an example of this.)
Days are short, yes, but the point of this is that any given day can be retried as often as you like. This is intended to make the player formulate an objective or objectives to carry out on that day and then allow them to try them, and if they fail, allow them to try again with the new knowledge they have gained. There is enough extra time available to allow the occasional day to be cocked up or wasted in the pursuit of building up your numbers or tracking down an elusive part early on.
There may be few units, but seeing as the three colours times three types (leaf, bud, flower) and the addition of bomb-rocks already stretches the interface to the limit of legibility and managability via the joypad, adding any more unit types would have surely offered diminishing returns.
There is a problem of repetition, but bear in mind that groups of Pikmin can be left to perform tasks autonomously, allowing you to juggle your attention between a few different objectives during the same time. However I will admit that when these tasks are basically housekeeping it can get a bit dull.
It is difficult to command the Pikmin, but to an extent that is intentional, and part of their character. They are fairly mindless, and they need to be wrangled carefully to prevent them killing themselves. In effect, this is very similar to the Lemmings games. Carelessness is punished ruthlessly (with drowning being a good example) however I feel that the implementation of bomb-rocks (which can annihilate your Pikmin if dropped accidentally) is a little unfair. It is also possible to rescue red and yellow Pikmin from drowning, if you're quick, but you're really meant to leave them well away from water most of the time anyway...
And finally, the problem of collecting your Pikmin by sundown. Well, firstly you don't need to bring them back to the onion manually, you just need to have them under the player's control at dusk. Secondly, this mechanic prevents players stockpiling ridiculous numbers of Pikmin throughout the game. And thirdly, if any Pikmin are left out in the wilds in large numbers, they didn't get there by themselves, did they? (Yes, most of the game's shortcomings can be argued against in this infuriating fashion. The style of gameplay won't appeal to everyone- it has driven me to distraction at times- but some people really are into this stuff.)
If I was to make one major criticism of the game, it is that it contains less in the way of puzzles than I expected. All the items that the Pikmin can interact with have basically one use, and although there is some variation in the enemies, strength through superior numbers is nearly always the key to beating them.
I haven't noticed any glitches (in a technical sense), but will add my support to the opinion that the game ultimately lacks depth. It is fun and (perhaps surprisingly) a good game to play in a social environment given a few hours to spare. It's probably the only game that my mum has pestered me to buy (in flat contradiction to the natural order of things) as well. Not a classic then, but certainly worthy of your attention (although perhaps try before you buy).