Hey Oli. I'll hand my opinion to you.
---The Good---
Market Combat Ability
The Wii U is a very capable system. Given what we know about the system on a specification level, and what developers have been able to achieve with the 2 odd years they've tinkered with it, the Wii U is certainly going to be able to hold a better light to the upcoming gen race than the Wii was able to (of course, I'm referring to appeal among gamers as opposed to appeal among consumers). However, that last part is more or less my assumption and isn't proof of how the future swings.
The Gamepad
It's a pretty nice piece of kit. It does make web browsing through the Wii U a breeze thanks to the touchscreen. It does offer more game options that competitor devices haven't been able to produce. It lasts decently enough (I think the 4-6 hours is good enough for a single sitting). A lot of games offer the ability to Off-TV play, which is possibly my favourite thing about the system as a whole. It seems like a simple concept, but the ability to not have a TV to operate means a lot in family rooms and during travels. (Yeah, I've played mine in the car one time. Pretty sweet.)
The Software
You'll find a lot of the software library to be fun, I guess. I'll admit, I'd rather play something heavy that you get from other consoles, but that's my personal preference. You also find that Wii U versions of games have their little exclusive things, not necessarily just with Gamepad controls but in content as well. Not necessarily mass amounts though. There are still some great incoming titles yet to be released as well.
The System
By system, I mean the interactive bits and bobs you can access almost at all times. The pieces that stay the same. The internet browser is allegedly fast, the main interface is nice and retains that channel effect that the Wii had, Miiverse is a nice message board and Miis are back, if that's your thing.
---The Bad---
Just a heads up, I'm going to be a lot more critical here than what was above.
Market Combat Ability
The marketing of the Wii U has probably been the worst thing about the console. Originally, the console has been stated to play the games that the gamers want to play. For this, Nintendo needed to have a lot less of the casual audience target, and more towards the people who game on a regular basis. I'm not gonna say they completely fuddled this up, but they haven't done spectacular in this area at all. They've hugged too tightly to the image of a family console, without really pushing into the kinds of things that a lot of people wanted from the console. With the PS4 and the Xbox One just around the corner, you'll find that the head start that the Wii U had in terms of advertisement not necessarily wasted, but misused. The Wii U might have had an early start, but they've set the pace too slow in my opinion.
The Gamepad
There are a number of problems with the Gamepad. First, is the resistive touch. A lot of people will say it's not really a concern, but I think that a lot of developers will feel that it's a missed opportunity, and it will show (or rather, not show) in the games that actually are developed by them. The battery life can be an issue, but you are supposed to break every hour or two after all (luckily, the Gamepad Pro Controller last unbelievable hours). A lot of developers seem to be doing very little with regards to using it, or just not at all. I think the worst negative here though, is when you have games where you have no choice but to use the Gamepad, and there is no Off-TV Play. Games like ZombiU and Batman Arkham City Armoured Edition feel wrong without a Gamepad Pro Controller as well as the low battery life of the Gamepad should you play a long session.
The Software
I feel the real miss here is the lack of software. That's not to say there aren't any decent Wii U games, just the right they are being pumped out is slow. The Wii U is receiving 'enhanced' ports at more cost than other counterparts. Some games have not received DLC when there really isn't no reason to do so. Even a year or two in, Call of Duty Ghosts wasn't able to have all the base functions that it's Xbox 360 or PS3 counterparts did.
What we have is a horrible cocktail where: developers are unsure of what to do with their Wii U titles, the few things they do know what to do they can't fully implement because their knowledge of the system is still too poor, they lack interest in detailing Wii U games because of the low sales (thanks to the marketing teams of Nintendo), and developers being intimidated at the prospect of making a Wii U only title because they can't port it to everything else and maximise sale.
I mean, in the end, it's all business. Sad business indeed, but I'm gonna be honest. There is no singular fault. The percentages are irrelevant, but it is the unification of these faults that make the Wii U seem such a shocking investment/development plan.
The System
Okay, just a few things. These are mostly personal and aren't necessarily a shared opinion like a lot of the other stuff.
Miis still feel limited. They seriously could've made a more complex and personal addition to it, and didn't really try. I understand simplicity, but hey, it's a digital representation of yourself. How would you not want to spruce yourself up?
The Miiverse feels clunky and too linear instead of a more free flowing place. Needs to be structured better.
There is no universal reward system. The trophy whore within me is screaming. People can tell me to have fun all they want. I do by trying to get these little buggers. That's actually a way of having fun as well. But it pains me to see developers try to make these big open games and only really having the drive to taste a portion of it. People will pay whatever amount they pay for Call of Duty titles and don't touch the Campaign, which to me sounds stupid because you paid for it, why are you only touching half the game, or rather, why did you pay double for a game? It doesn't make sense. Sure, it's not the most thrilling thing on the planet... Point is, I find reward systems to be an answer to the unplayed. Nintendo is smart enough to make a reward experience that's worth playing for, so why didn't they do it? It makes no sense.
The eShop is a mess. What's worse, is that it still feels catered to people using credit cards. The maximum value of a top up card I can get is $30. I'd need to buy 3 of those to download a particular title like Ken's Rage 2 for example. It's not the easiest format to explore through either. I honestly thought Nintendo would be the ones to make something that feels nicer than what the Xbox 360 and PS3 have. They didn't.
Hooking up with other players isn't nearly as easy on the Xbox 360 and the PS3.
---
And that's how I feel about the Wii U. It is practically my Black Ops II/Ken's Rage 2 box.