Wealth Engine provides solid reporting that we have found to be generally accurate. When there's a match to find, WE has generally found it, and while the data isn't always perfect, it's a good indicator for where to start with fundraising and targeting mid and major level donors.
Batching data in and out of WE is frustratingly opaque, and the customer service leads something to be desired. Sales team also employs some rather shady 'used-car-dealer' negotiation styles - we were given the classic "we have this sale until friday at 4pm, it's the lowest ever, but you have to agree now, and we definitely can't offer the sale price next Monday which is when we are available to answer your questions about the product."
One final dislike - WE changed the way their data was reported a year or two ago, meaning there are now discrepancies between our data sets, which makes it hard to do comprehensive reporting for multiple years.
The largest benefit we've seen is an easy way to see help classify our donors into tiers - general, mid, major.