The US stock market is one where active fund managers tend to struggle to beat the Index. So using a tracker fund to get mainstream exposure to the US market seems a sensible strategy.
The key when buying a tracker fund is that it tracks an appropriate index accurately and cheaply, something the db X-trackers S&P 500 ETF (exchange traded fund) has done well to date.
db X-trackers is the arm of Deutsche Bank (Germany's largest) that offers exchange traded funds, so even though not a household name they're part of a very large institution. Probably just as well as like all ETFs (that I'm aware of), db X-trackers funds are not covered by the Financial Services Compensation Scheme (FSCS). So, unlike investments covered by the FSCS, in the very unlikely event you lose money (for a reason other than poor investment performance) you won't be entitled to any compensation.
The fund is allowed to use financial derivatives track the index (as well as holding actual shares) which adds a bit of risk, as the other financial company (called a 'counterparty') might not pay whatever they've promised as part of the derivative deal. The risk probably isn't especially high, in any case EU investment rules restrict such exposure to 10% of the fund per counterparty, but it's something to be aware of.
So that's the nitty gritty out of the way, what about charges? With total annual charges (as measured by the total expense ratio) of just 0.2% this fund looks something of a bargain. And if you want a US tracker fund and can live with the counterparty risk mentioned above, then I think it is.
Bear in you'll need to buy the ETF via a stockbroker, so you'll have to pay dealing fees to buy and sell, but at least there's no stamp duty. As the fund is traded on the London Stock Exchange so should be available via most stockbrokers.
Because ETFs are domiciled (i.e. based) overseas it's important to check they have either 'distributor' or 'reporting' status, as without this any gains will be taxed as income which is generally not very efficient. Thankfully this fund has reporting status, so it'll be taxed in the same way as a UK based fund. Note: dividends are re-invested into the fund in a similar way to unit trust accumulation units.
The S&P 500 Index invests in 500 of the largest US companies. It's weighted by company size, so the largest companies will dominate, but overall it has a pretty good spread across a number of sectors, including energy, manufactured goods, financials, technology, pharmaceuticals, food, tobacco and healthcare.
When investing in the US you obviously need to be aware of currency risk. That is, dollar/pound currency movements will affect the value of your investment independent of stock market movements. This applies to most actively managed funds too, as few fund managers bother insuring against (i.e. hedging) currency risk.
All in all this looks a very cost effective way to invest in the US stock market. Just make sure you deal via a low cost stockbroker and understand the nature of investment counterparty risk.
Note: the review rating relates to the fund itself and not the investment prospects for the US stock market.