What is the Samsung Galaxy S4?
As explained in greater depth here, the Galaxy S4 (pictured) is Samsung's newest flagship smartphone and the successor to the Galaxy S3, which did very well - even outselling Apple's iPhone 4S for a while.
The S4 looks almost identical to the S3 at a glance, but Samsung has crammed in a load of new features and tech to justify its hefty £579 (SIM-free) price tag.
Who's it good for?
If you're currently an S3 user and due an upgrade, the S4 may be right up your alley because it improves on its predecessor in almost every way, but retains the look and feel of the S3.
What's more, Samsung's Galaxy range appears to be chipping away the iPhone fan base, so the S4 may also have an appeal to iPhone fans growing tired of Apple's yearly, incremental updates to its flagship handset.
As with any new, top-of-the-range smartphone, the Galaxy S4 is expensive. It's possible to pick up a SIM-free S4 for £579, but then you'd need to sign up for a SIM-only deal.
Virgin Mobile's rolling one-month SIM-only deal is one of the best value tariffs, offering 1,200 minutes, unlimited texts and a 1GB data allowance for £12 a month.
But if you don't want to fork out nearly £600 up front for the phone (and who could blame you), you'll have to sign up for a pay monthly deal...
Sign up for a two-year contract and you'll get the phone for the lowest up-front and monthly costs, but you'll be locked in for 24 months.
For example, for £99 up-front and then £36 a month, T-Mobile is offering 2,000 minutes, unlimited texts and an unlimited data allowance. Over the course of the contract, this will cost you a total of £963.
O2 will give you an S4 for £69.99 up-front and then £37 a month, and while you'll get unlimited calls and texts, data is capped at 1GB. Over two years this will cost you £957.99.
You can get the S4 for free from O2 if you pay £37 a month, but the allowances on this 24-month contract are less attractive at 600 minutes and 750MB of data - though texts are unlimited. Over two years this will cost £888.
Tesco Mobile will give you a free S4 on a two-year contract if you spend £30 a month (£720 in total), but you'll only get 250 minutes, 5,000 texts and 500MB of data. For £35 a month (£840 in total) you'll get a free S4, and Tesco will double your data allowance to 1GB.
EE is the only network currently offering super-fast 4G downloads. According to its website, EE's best deal on the S4 will give you unlimited calls and texts and a 1GB data allowance if you pay £79.99 up-front and then £41 a month for two years, bringing the total cost to £1063.99.
Bear in mind, however, that while EE's 4G coverage is pretty impressive at around 50% of the country, you won't be able to use super-fast 4G unless you live in a 4G area. Read more about that here.
Vodafone will do you a 12-month deal on the S4 for £139 up-front and £43 a month (total cost: £655). This sounds good, but the tariff's allowances are pretty low at 600 minutes and 500MB. UK texts are unlimited, however.
EE has a 12-month deal for £69.99 up-front which will give you a respectable 8GB data allowance and unlimited calls and texts. It'll cost you £66 a month though, bringing the annual total to £861.99
Any other catches?
The handset has only been out for a week or so, and while reviews have generally been glowing, the phone has been criticised by some for feeling a bit cheap, for its relatively short battery life and for its user interface, which can be confusing.
Also, some users have reported only having around 9GB of available storage on their 16GB handsets. It's thought that Samsung's own software, which sits on top of the core Android Jellybean operating system, could be taking up a few gigabytes of the phone's internal memory.
What's the verdict?
The S4 has more than enough to continue to take the fight to Apple but, as ever, you're still going to fall into either the Apple or Android camp.
The fact that Samsung has slapped an overlay on top of the Jellybean OS isn't going to help the Android cause, because Android is already at a point where it rivals Apple's much-prized ease-of-use - and Samsung's software only complicates matters.
And of course the S4 doesn't come cheap. At the time of writing, Vodafone's 12-month deal for £655 appears to be the cheapest, but that's certainly not cheap, and its allowances are quite low.
If you want bigger allowances, you'll pay for it in higher monthly costs. If you want to pay less for the handset up-front, you'll pay for it in higher monthly costs, and if you want to pay less each month, you're going to have to compromise on allowances or pay more up-front.
You could most likely get an iPhone 5 for less, but you won't get any of the S4's unique features like its eye-tracking technology. Plus, the iPhone 5S announcement is likely this summer, so your Apple handset would quickly become, in smartphone terms, out of date.
If you don't like the idea of being tied into a 24-month contract, O2's new Refresh tariff might appeal.
Basically, your monthly payments are split into two: one for the handset itself and one for your calls, texts and data (airtime).
If, 12 months into the 24-month contract, you want to escape the deal, you'll only have to pay off the phone component of the contract to get out, and not stump up for the airtime you won't use.
So if, for example, you were paying £42 a month (£17 for your airtime and £25 for your phone) and wanted to leave after a year, you would only have to pay off the remaining 12 months' phone payments totalling £300 - which you could probably get by recycling the handset anyway.
On any other network, buying out of a similarly-priced tariff would cost you the full monthly price (£42) for the remaining months, totalling £504.
Please note: Any rates or deals mentioned in this article were available at the time of writing. Click on a highlighted product and apply direct.