I have the TTi TF930 which I bought as an ex-demo unit for £200.
The reasons I went for it was I wanted 10 digits and I wanted a counter that would go down below 1 Hz and have a reference input so I could stick my 10MHz reference on the reference input and measure the 1pps from a GPS module and then tune my 10MHz source.
For this purpose the TTi TF930 works well. Other pluses are it is a continuous reciprocal counter (i.e. it doesn't reset itself between readings but continues to count), it is very light and low power so it can operate from USB or from its internal batteries and it is very easy to carry around.
The negatives are the LCD display isn't even backlit so is not easy to see in some conditions and it is a bit slow if you want the full 10 digits (i.e. you need to set the 100 second gate).
As others have said, you can get good 8 digit or 9 digit counters with bright displays more cheaply on e-bay which are probably a better choice for direct frequency measurement. I personally didn't go for these because they tend to have a minimum frequency of several 10s of Hz and I already have 6 digits on my scope counter so I wanted a significant step up from this.
What I'd really like is one of top-of-the-line Agilent series at 12 digits a second and 20 psec resolution but these are ten times the price even second hand.
EDIT: another negative, which rather annoys me, is that the 10MHz reference input requires quite a high amplitude (at least 1Vrms I think) to be recognized so I had to build a little video amp just to get my 10MHz OCXO to become a reference source and you can't take the reference output of say the Agilent 33522A and feed it straight into the reference input of the TTi. There is also no reference output so it is difficult to daisychain.
Another plus though is that it can be connected to a computer for logging readings and so on, but I've only managed to do this successfully using a dumb terminal on a Windows XP laptop - I've not yet managed to get it talking to my Windows 7 64bit workstation. I've not tried for a while though, TTi may have produced an updated driver.
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