Coincidently I am working on another project now that uses BitCoin... Fad or not Bitcoin serves a very strong need for me an many others.
Bitcoin shows us some cool stuff, but it's not sufficient for real-world everyday use. It will be an ancestor to a truly disruptive online currency imo. The network has too many fundamental inaccessibilities to make it plausible outside the elite nerd and/or money laundering sector.
Just because I didn't rattle all of these off doesn't mean "I don't have any actual reasons for it". I suggest you ask more politely for exposition next time.
The blockchain is huge, and splitting it is ad-hoc patchwork. The network was obviously not designed for such a thing and I'm not really optimistic about it. At this point it takes 6+ days to bootstrap a bitcoin client.
There is still no easy integration method with extant payment systems. It takes weeks to transfer money in and out, or you have to make the trade in person. In many cases you must supply a lot of personal documentation to do anything meaningful on the exchanges. This could hypothetically be resolved, but given the stubbornness of banks and the fact that no one has done it yet gives me relatively little hope.
The system of block verification makes it impossible to do truly instantaneous transfers. This is a big one. Double-spend attacks are real, and people want their transactions to go through immediately.
The system is vulnerable to 51%+ attacks. Not a problem thus far, but I seriously believe it's a huge gaping weakness if btc wants to be taken seriously.
Mining is prohibitively difficult for the layman. These days not even reasonable single-home GPU farms are going to be enough to compete. The reward for mining is diminishing quickly.
Many of the perceived benefits of bitcoin are illusory or misunderstood. For instance, people claim bitcoin is private and/or anonymous when in reality, every transaction ever made with bitcoin is published publicly. This has serious implications for practical privacy deployments. The currency, like the US dollar, still has a baked-in elite class, which is the group of people that own the most compute power. This could hypothetically change, but in real life, it probably won't.
I could keep going (have barely mentioned client-side stuff), but I think this is sufficient. I have "actual reasons" for it. I understand the bitcoin guys know about all of this and think it's not a problem, but I disagree with them. A currency that doesn't have (at least most of) these issues will be super awesome, and bitcoin is an important predecessor, but it's not the end of the story.
This is only an issue if you're running a full-node. If you want to place limited trust in others, you can use a light client (like Electrum or blockchain.info), which are very easy to set up.
> There is still no easy integration method with extant payment systems
Coinbase and Bitpay are making huge strides in this area, so I don't agree with you that "no one has done it".
> The system of block verification makes it impossible to do truly instantaneous transfers. This is a big one. Double-spend attacks are real, and people want their transactions to go through immediately.
The legacy financial system takes upwards of 30 days for a transaction to truly be settled. The fact that bitcoin transactions can be provably non-reversible after just 1 hour is an enormous technological leap.
> The system is vulnerable to 51%+ attacks
51% attacks will only get more expensive as time goes on. Also, in the event of an attack, there are strategies  that can be employed to minimize their impact.
> Mining is prohibitively difficult for the layman.
I don't think this matters for wide-spread acceptance. Most people don't mine for gold, but they still happily use it as a medium of exchange.
What are you talking about here?
> The network was obviously not designed for such a thing
Are you talking about Section 7 "Reclaiming Disk Space" and section 8 "Simplified Payment Verification" in the initial design document, which have a profound influence on the design— as Bitcoin uses a hash tree to aggregate transactions instead of just a simple hash in order to accommodate those design features?
> There is still no easy integration method with extant payment systems.
Unfortunately existing online payment systems are highly reversible for months after the transaction completes. This is problematic for many kinds of merchants and it's one of the reasons that digital goods sales on the Internet have mostly been a failure outside of a few special marketplaces.
> In many cases you must supply a lot of personal documentation to do anything meaningful on the exchanges.
This is common anti-money laundering law conformance— same thing you deal with w/ paypal... not exactly a limitation of Bitcoin.
> The system of block verification makes it impossible to do truly instantaneous transfers.
Nothing requires you to do payments in Bitcoin by directly transacting on the Bitcoin network. Scalability and speed require that not all transactions are made directly— likewise, the USD is a dumb piece of paper that can't be sent over electronic networks... and yet the USD is a widely used currency. You can do instant transaction trivially in Bitcoin, e.g. using mtgox codes and less centralized systems can be built if anyone cares.
> The system is vulnerable to 51%+ attacks.
Can you suggest any currency or system of agreement that doesn't have an analogous weakness?
At least in the context of Bitcoin the things a majority hashpower attacker can do are strictly limited: they can reorder transactions (and only recent ones unless they are a very big supermajority).
Compare this to a government created currency which can be inflated boundlessly by a small percentage of the population choosing to mint a trillion dollar 'coin' on a political whim.
> single-home GPU farms are going to be enough to compete
Mining's rewards are linear. Participants make on average their share of the new coin relative to the computing power they provide to secure the currency. And indeed, it's specialized. Is the USD uncompetitive because printing your own gets you imprisoned or gold uncompetitive because gold mining is hard?
Get a job, Kid. It's a currency not a free-money-for-nothing-thing.
> Many of the perceived benefits of bitcoin are illusory or misunderstood.
Well, that's true of many things.
> every transaction ever made with bitcoin is published publicly
Not so— a significant fraction of transactions are made off the blockchain, perhaps even a majority. Even within the blockchain the transactions are pseudonymous.
> I have "actual reasons" for it.
You may, but many of your perceived weaknesses are also illusory or misunderstood.
> A currency that doesn't have (at least most of) these issues will be super awesome, and bitcoin is an important predecessor, but it's not the end of the story
The most important difference between Bitcoin and your hypothetical perfect digital currency is that Bitcoin exists and it works. Satoshi didn't waste time waxing philosophical on the internet, he shut up and wrote code. If there is one thing you could learn from Bitcoin, this should probably be it.
You're taking a lot of offense here over a disagreement. I do write code, and I respect bitcoin a lot, as I've said already three times now. I have and use bitcoins and think it's a cool thing they're doing. I'm glad Sathosi coded it despite its issues. I just don't believe these issues are as minor as the btc community believes they are, and I don't believe the proper response to criticism is "oh yeah well you can't do any better so shut up".
But FYI MintChip transactions are anonymous.
It is a digital form of cash.