Are pensions any good? The main problem is that there's no way of knowing, when you start out, what level of income you will obtain when you retire. Worse still, is that even when close to retirement or in retirement, you still won't know from one year to another (OK - 3 years) what your level of income will be, unless you purchase an annuity. At present, annuity rates seem pretty poor value, but at least they will give a degree of stability. The downside being, the more stability you require, the greater the cost - i.e. inflation proofing).
The pro's and con's have been largely explained by previous posters, so it's really down to the individual to decide if the upfront tax relief is compensation enough for the future restrictions which will be imposed, and the inherently unpredictable nature of those restrictions.
My personal view is that, as much as I hate pensions, I can save about 42% in tax (income tax, employers & employees NI) on contributions. So sacrificing £0.58 of income buys me £1 of pension. However, 25% of that £1 can be recovered, so every £0.33 of pension contribution will buy me £0.75 of pension. In other words an instant gain of 127%. For me that's a no-brainer, but for others, I know they wouldn't touch pensions with a barge-pole, due to the loss of flexibility.
Another factor for me, is that I'm already drawing down from my SIPP, so that I can salary sacrifice, thereby offsetting some of my pension contributions against pension income. This gives a neutral position on income tax, but means that the savings in NI contributions still go straight into the pension fund.
My final thought is that I don't wish to give my hard earned money to an insurance company, so I am resistant to buying an annuity, especially at current rates. Drawdown should allow me to retire sooner, due to the higher income I can expect (although this might change) and, hopefully, lead to a rising income over time. My aim will be to withdraw as much as possible from my SIPP, within the 20% tax rate, in order to run down the fund over time - assuming I live long enough!